Quick answer: choose Django when you are building a full web application with users, roles and permissions, an admin or back office and a relational data model. Choose FastAPI for typed, async-first APIs, microservices and ML or LLM model serving. Many teams run both: a Django core for the product and FastAPI services for model inference or high-concurrency endpoints.
Django vs FastAPI is one of the most common decisions a Python team makes, and most comparisons frame it as a contest. It isn’t one. Both frameworks run serious production systems, and both are actively developed. The useful question is how much of your product is an API, and how much is a full application with users, permissions, content and back-office screens. The answer to that question settles most of the choice before anyone opens a benchmark.
This is the first thing we look at when we scope custom web application development for a client, because it shapes timelines, team structure and what you will have to build by hand. Our Python and Django development team works with both frameworks every week, often on the same project, so this guide tries to give each one a fair hearing rather than pick a side in advance.
The guide is written for CTOs, founders and tech leads who are choosing a Python backend framework in 2026. Inside: what each framework is today, a 12-row comparison table, an honest answer on performance, the real architectural differences in async and the data layer, what Django 6 changed, the middle ground of Django REST framework and Django Ninja, when to choose each, how to combine them, a product-type matrix, AI and LLM backends, cost, migration and hiring, common mistakes, an FAQ and a conditional verdict. If you have not yet settled on Python at all, start with our Node.js vs Python backend comparison.
What is Django?
Django is a “batteries included” Python web framework, open source under the BSD license and in public use since 2005. It ships with almost everything a typical web application needs: an object-relational mapper (ORM) with schema migrations, authentication with users, groups and permissions, an automatically generated admin interface, forms, a template engine, sessions, caching and a set of security protections such as CSRF tokens, clickjacking protection and safe password hashing. Django follows the model-view-template (MVT) pattern, and its conventions mean that a developer who knows one Django project can find their way around another quickly.
The framework’s centre of gravity is the data model. You describe your entities as Python classes, and Django generates the database schema, the migrations, the admin screens and much of the form handling from that single definition. That is why Django is so productive for products with many related entities and internal users who need to manage them.
The 2025–2026 state of Django matters for this comparison. According to the official Django download page, the latest release line is 6.1 (6.1.2 at the time of writing). Django 5.2 is the current long-term support (LTS) release, with extended support until April 2028. Django 6.0 is supported until April 2027 and 6.1 until December 2027, and the next LTS, 6.2, is planned for April 2027 with support to April 2030. Versions 5.1 and older are unsupported. Django 6.0, released on 3 December 2025, added built-in Content Security Policy support, template partials and a built-in Tasks framework, and supports Python 3.12 to 3.14.
- Strengths: admin, ORM, migrations and authentication out of the box; secure defaults; a predictable LTS release cycle; a very large ecosystem of reusable apps; fast delivery of full applications with back-office screens.
- Watch-outs: async support is real but still partial (transactions do not yet run in async mode); API-only projects carry framework weight they do not use; a separate library such as Django REST framework or Django Ninja is needed for a modern typed API layer.
What is FastAPI?
FastAPI describes itself as a “modern, fast (high-performance) web framework for building APIs with Python based on standard Python type hints”. It is built on two other libraries: Starlette for the web layer and Pydantic for data validation and serialization. You declare request and response shapes with ordinary type hints, and FastAPI validates incoming data, converts it to Python objects, serializes responses and generates an OpenAPI schema from the same code.
That schema powers one of FastAPI’s most visible features: interactive API documentation is available automatically, with Swagger UI at /docs and ReDoc at /redoc. Because the framework is based on the open OpenAPI and JSON Schema standards, client SDKs and contract tests can be generated from it. FastAPI also has a built-in dependency injection system, which is a clean way to share database sessions, authentication checks and configuration across endpoints. It is async-first and runs on an ASGI server such as Uvicorn. The project’s own site claims performance “on par with NodeJS and Go” and development that is 200% to 300% faster; those are the project’s claims, not independent measurements, and we come back to performance below.
What FastAPI does not include is just as important. There is no built-in ORM, no migrations tool, no admin panel and no user model. Teams typically assemble SQLAlchemy or SQLModel for data access, Alembic for migrations and an authentication library or identity provider. FastAPI is also still on 0.x versioning: according to PyPI, the latest release is 0.162.0 (23 October 2026), with the classifier “Development Status :: 4 - Beta”. It requires Python 3.10 or later and is MIT-licensed.
- Strengths: type-hint-driven validation and serialization; automatic OpenAPI docs; async-first design suited to I/O-heavy and streaming workloads; dependency injection; a small surface that is quick to learn for API work.
- Watch-outs: no ORM, admin or auth built in, so you assemble and maintain that stack yourself; 0.x versioning means you should pin versions and read release notes before upgrades; blocking code inside
async defendpoints can stall the whole server.
Django vs FastAPI at a glance
The table compares the two frameworks on the factors that change a product decision. Each row is explained in the sections that follow.
| Criterion | Django | FastAPI |
|---|---|---|
| Type and philosophy | Full-stack, batteries included, convention over configuration | API micro-framework, assemble the stack you need |
| Primary use | Complete web applications with users, admin and back office | Typed REST APIs, microservices, model serving |
| Async model | Sync by default; async views and async ORM methods on ASGI | Async-first on ASGI (Starlette, Uvicorn); sync endpoints run in a threadpool |
| Data layer and ORM | Built-in ORM with migrations | None built in; usually SQLAlchemy or SQLModel plus Alembic |
| Validation and serialization | Forms; serializers via Django REST framework or schemas via Django Ninja | Pydantic models declared with type hints |
| API documentation | Through add-on libraries | Automatic OpenAPI, Swagger UI at /docs, ReDoc at /redoc |
| Auth and admin | Users, groups, permissions and admin panel included | Security utilities only; auth and any admin are added separately |
| Background jobs | Tasks framework (6.0) standardizes the API; Celery and similar for workers | Simple in-process background tasks; Celery or a queue for real jobs |
| Security defaults | CSRF, clickjacking, password hashing, built-in CSP since 6.0 | Input validation by design; the rest depends on what you add |
| Release and support model | Published LTS: 5.2 to April 2028, next LTS 6.2 in April 2027 | 0.x versioning (0.162.0, October 2026); pin and test upgrades |
| Learning curve | Larger surface; conventions take time to master | Quick start for APIs; architecture decisions are left to you |
| Popularity (JetBrains 2024) | Used by 35% of respondents | Used by 38% of respondents |
Popularity figures come from the JetBrains and PSF Python Developers Survey 2024 (responses collected in October–November 2024, more than 30,000 respondents, about 25,000 after filtering), where FastAPI was used by 38%, Django by 35% and Flask by 34% of developers. They describe how widely each framework is used, not which one is better for your product.
Is FastAPI faster than Django?
For I/O-bound APIs, FastAPI running on an ASGI server typically handles more concurrent requests per worker than a traditional synchronous Django deployment. The gap narrows when Django runs async views on ASGI, and in most real products the database, not the framework, is what limits throughput. Here is the answer by workload, without invented requests-per-second figures.
I/O-bound APIs
Most API endpoints spend their time waiting: on the database, a cache, a payment provider, another internal service or an LLM API. FastAPI is designed for exactly this. An async def endpoint yields control while it waits, so one worker process can keep many requests in flight. A classic synchronous Django deployment on WSGI handles one request per worker thread or process at a time, and you scale by adding workers. For endpoints that call slow external services, such as payment gateways, webhooks or model providers, that difference shows up quickly in the number of workers and the memory you need.
Where Django closes the gap: ASGI, async views and async ORM
Django is no longer synchronous only. Its async documentation describes async views written with async def and an async ORM interface through a-prefixed methods such as afirst(), acreate() and asave(), plus async for over querysets. To get the full benefit, Django must run under ASGI. Under WSGI, async views still work, but each one runs in a one-off event loop, so you get the syntax without the concurrency. A Django project deployed on ASGI with async views on its slow, I/O-heavy endpoints can serve those endpoints in a way much closer to FastAPI.
What actually limits throughput
In most products we profile, the framework is not the slowest part of a request. Slow queries, missing indexes, N+1 query patterns (one query for a list, then one more query per item), large serialized payloads and chatty calls to other services cost far more time than the framework overhead. A FastAPI endpoint with an N+1 problem is slower than a Django endpoint that uses select_related correctly. Serialization also matters: Pydantic v2 validation is fast, but returning thousands of nested objects is expensive in any framework. Fix the data access pattern first; then the framework difference starts to matter.
Async, ORM and the data layer: the real architectural difference
The deepest difference between Django and FastAPI is not speed but where the data layer lives. In Django, the data layer is part of the framework: ORM, migrations, admin and forms all come from the same model definition. In FastAPI, the data layer is a separate set of libraries you choose and wire together. That shapes how async works, how validation works and what you will maintain.
Django’s async limits. The Django documentation is explicit about what is not finished yet. “Transactions do not yet work in async mode”: if a piece of code needs a transaction, you write it as a synchronous function and call it with sync_to_async(). Persistent database connections set with CONN_MAX_AGE should be disabled in async mode, and the docs recommend connection pooling instead. And, as noted above, async views only deliver real concurrency under ASGI. None of this is a blocker, but an async Django codebase has to mix sync and async code deliberately, and the team needs to know where the boundaries are.
FastAPI’s async model. FastAPI is async from the start, and the usual data stack is async too: SQLAlchemy’s async engine or SQLModel on top of it, with an async database driver. The trap is blocking code. If you call a synchronous database driver, a synchronous HTTP client or a heavy CPU function inside an async def endpoint, it blocks the event loop and every other request on that worker waits. FastAPI’s answer is simple: declare such endpoints with plain def, and FastAPI runs them in a threadpool; or push the blocking call into a thread or a separate worker. Teams new to async often get this wrong in the first weeks.
Validation: Pydantic v2 vs Django serializers and forms. In FastAPI, a Pydantic model is both the validation rule and the API documentation: the same class checks incoming JSON, converts types and produces the OpenAPI schema. In Django, validation lives in forms for server-rendered pages and in serializers if you use Django REST framework, while the ORM model is a separate definition. Pydantic models are explicit and portable; Django serializers are tightly integrated with the ORM and can generate a lot from a model with little code. Both work well. The practical difference is that in FastAPI you usually keep two sets of classes (ORM models and Pydantic schemas) and map between them, which is the cost of not having a built-in ORM.
Deployment. Both frameworks deploy the same way in modern infrastructure: in containers behind a load balancer, with an ASGI server such as Uvicorn for FastAPI and for async Django, or a WSGI server for sync Django. Our cloud and DevOps team usually settles the server, worker count and connection pooling together with the framework choice, because those three decide real-world throughput.
What changed in Django 6 and why it matters for this choice
Many Django vs FastAPI articles were written around 2023, when Django’s async story was thin and anything outside the request cycle meant installing Celery. Django 6.0, released on 3 December 2025, narrowed several of those gaps. None of them turns Django into FastAPI, but they change where the line falls.
- Built-in Tasks framework. Django 6.0 adds
django.tasks: you decorate a function with@taskand call.enqueue()to run it “outside the HTTP request–response cycle”. The framework standardizes the API for defining and queuing tasks; you still configure a backend and run workers to execute them in production. The value is a common interface, so libraries and apps can define background work without each depending on a specific queue. - Content Security Policy. CSP is now built in through
ContentSecurityPolicyMiddlewareand theSECURE_CSPsetting. For applications that serve HTML, this adds one more security control that previously needed a third-party package. - Template partials. The new
{% partialdef %}and{% partial %}tags let you define and render named fragments inside a template. That fits server-rendered interfaces that update parts of a page, such as those built with HTMX, without a separate JavaScript front end. - Modern Python. Django 6.0 supports Python 3.12 to 3.14, so new projects run on current interpreters.
- Async ORM maturity. The async ORM interface covers the common query and write operations. Transactions remain the main gap, which is why
sync_to_async()is still part of everyday async Django code.
For the decision, this means two things. First, “Django can’t do background work without extra infrastructure” is less true at the API level, though you still need a worker. Second, Django has become a stronger choice for server-rendered products that want modern interactivity without a single-page app.
Middle ground: Django REST framework and Django Ninja
The choice is not always “Django or FastAPI”. If you want Django’s ORM, admin and authentication but also need a proper API, two libraries let you stay inside Django.
Django REST framework (DRF) is the long-established way to build APIs on Django. It provides serializers, viewsets, routers, authentication and permission classes, throttling and a browsable API. It is very well known among Django developers, and its serializers can generate much of an API directly from your models. It is mostly synchronous and less type-hint-driven than FastAPI, but for CRUD-heavy APIs on top of a Django data model it is often the fastest route.
Django Ninja brings a FastAPI-like style to Django: you declare endpoints with type hints and Pydantic-based schemas, and it generates OpenAPI documentation automatically. It runs inside your Django project, so it uses the Django ORM, settings, authentication and admin. For teams that like FastAPI’s developer experience but need Django’s back office, it is a strong option.
This middle ground beats a separate FastAPI service when your API mostly reads and writes the same data your admin manages, when you want one deployment and one authentication system, and when the team is small. A separate FastAPI service makes more sense when the API has a genuinely different workload, such as model inference or a high volume of concurrent long-lived connections, or when another team will own it. Whatever you choose, the API design itself matters as much as the framework; our comparison of REST API vs GraphQL covers that layer.
When should you choose Django?
Choose Django when the product is more than an API: when people log in, have different roles, and operators manage data through internal screens. These are the scenarios where it is the stronger default:
Admin-heavy CRUD, CRM and ERP
Systems with dozens of related entities and internal users get an ORM, migrations, permissions and a working admin panel from the model definitions, instead of weeks of custom screens.
Marketplaces and content platforms
Buyers, sellers, moderators and editors with different permissions, plus moderation queues and catalog management, map directly onto Django’s auth and admin.
An MVP that needs a back office on day one
When operators must manage users, orders or content from launch, the Django admin replaces a whole internal tool — see our guide on MVP vs full product build.
Regulated apps that need mature security defaults
CSRF protection, password hashing, permission checks and built-in CSP, all maintained on a published LTS schedule, reduce the security code you have to write and audit.
Server-rendered sites with HTMX
Template partials in Django 6 make interactive server-rendered pages simpler, which avoids a separate single-page app for many dashboards and portals.
When should you choose FastAPI?
Choose FastAPI when the product is mainly an API, when contracts and types matter, or when the workload is dominated by many concurrent requests that wait on other systems. These are the scenarios where it is the stronger default:
ML and LLM model serving, RAG APIs
Pydantic schemas for prompts and results, async calls to model providers and streaming responses make FastAPI a natural wrapper around inference and retrieval.
Microservices and internal service APIs
Small services with a narrow job stay small: no admin or template layer to carry, a clear OpenAPI contract and quick start-up in containers.
Public APIs where the OpenAPI contract matters
Partners and client teams get accurate, always-current docs at /docs and can generate SDKs from the schema, because the docs come from the code itself.
High-concurrency I/O: webhooks, streaming, WebSockets
Many concurrent, mostly-waiting connections fit the async-first design, as long as blocking calls are kept out of async endpoints.
API-only backend for a React, Next.js or mobile front end
When all UI lives in the client and no back office is needed, a typed API is all the backend has to be — see Next.js vs React for B2B web apps.
If the API is the product, our API development team usually starts from the OpenAPI contract and builds the FastAPI service around it.
Can you use Django and FastAPI together?
Yes, and it is a common, well-tested pattern rather than a compromise: Django owns users, permissions, the admin and the core business data, while one or more FastAPI services handle model inference, high-concurrency endpoints or a public API with a strict contract. Each side does what it is best at.
How the pattern usually looks. The Django application is the system of record. Operators work in its admin, users log in through its authentication, and its ORM owns the main schema and migrations. A FastAPI service sits next to it with a narrow job: run a model, answer a high-volume read endpoint, or stream LLM responses. Short, synchronous requests go over internal REST calls; long or heavy work goes through a message queue, with workers reporting results back. Each side can be deployed and scaled on its own.
Shared database or separate? The simplest option is for the FastAPI service to read the same database, usually through read-only access to a few tables. It is quick to build, but it couples the service to Django’s schema, so every migration has to consider both. The cleaner option is for the FastAPI service to own its own data and get what it needs from Django through an API or events. It costs more upfront and pays off when the services are owned by different people or change at different speeds.
Pitfalls to plan for. Two authentication systems are the most common problem: decide early whether FastAPI trusts tokens issued by Django or whether both use a shared identity provider. Duplicate models are the second: if the same entity is defined in Django and again in SQLAlchemy, keep a single owner for each table and treat the other side as a read-only consumer. Finally, two frameworks mean two dependency trees and two upgrade schedules. For a small team, the middle ground of Django Ninja is often enough; split only when the workloads are really different. Our guide on monolith vs microservices explains when a service boundary pays for itself.
Django or FastAPI by product type
The product you are building usually points to a sensible default. The table below is a starting point, not a rule.
| Product type | Recommended | Why |
|---|---|---|
| SaaS dashboard | Django (with DRF or Ninja), or FastAPI if the front end is a separate SPA and there is no back office | Accounts, billing, roles and internal tooling favour Django; a thin API behind a React app favours FastAPI |
| Marketplace | Django | Many user roles, moderation, payouts and catalog management map onto auth and admin |
| Fintech back office | Django | Permissions, audit-friendly admin and mature security defaults on an LTS cycle |
| AI assistant or RAG product | FastAPI for the AI service; Django if there is a product around it | Streaming and Pydantic schemas for inference; users, billing and content in Django |
| IoT ingestion API | FastAPI | High volumes of small, concurrent writes with strict payload validation |
| Mobile app backend | Either; Django if operators manage content or users | A pure API favours FastAPI; push campaigns, support tools and content management favour Django |
| Internal tool | Django | The admin alone often covers most of the requirements |
| Headless CMS or content API | Django | Editors need an admin and workflows; the API is a read layer on top |
Which is better for AI and LLM backends?
For the AI service itself — the endpoint that takes a request, calls a model or a retrieval pipeline and returns or streams the result — FastAPI is usually the better fit. For the product around the AI — users, subscriptions, content, permissions and the screens where operators review outputs — Django is usually the better fit. Most serious AI products need both layers.
Why FastAPI suits model serving. LLM calls are slow I/O: the service waits seconds for a provider or a local model. Async endpoints let one worker hold many such requests at once. Streaming responses let you send tokens to the user as they arrive instead of waiting for the full answer. Pydantic schemas give you strict, documented contracts for prompts, tool calls and structured outputs, which matters when model results feed other systems. And a small service is easy to deploy next to GPU or inference infrastructure.
Why Django still matters in AI products. An assistant or RAG product also has accounts, organizations, document libraries, usage limits, billing, feedback and audit trails. That is classic Django territory: models, admin and permissions. Teams that build all of it in FastAPI end up rebuilding the back office by hand. A frequent 2026 shape is a Django application that owns the product and a FastAPI service that owns retrieval and inference, connected by internal API calls and a queue for long jobs. Our generative AI integration team designs that boundary, and if you are still deciding how the model should learn your data, see RAG vs fine-tuning.
Cost, timeline and hiring: Django vs FastAPI
Neither framework is cheaper in general. What changes the budget is how much you get for free, how much you have to assemble and maintain, and how often you upgrade. These are the drivers we look at when we estimate a Python backend:
- Built-in back office. Django’s admin, authentication, permissions and migrations save weeks on any product with internal users and many entities. If you need those features, building them on FastAPI is real, recurring work.
- Pure API speed. For a pure API with no back office, FastAPI gets you to a documented, validated API quickly, and Pydantic schemas double as documentation. The cost moves to assembling the data layer (ORM, migrations, auth), making architecture decisions Django would have made for you, and keeping them consistent as the team grows.
- Maintenance and upgrades. Django publishes LTS releases with long support windows, so upgrades can be planned years in advance: 5.2 is supported until April 2028, and 6.2 LTS is due in April 2027. FastAPI is on 0.x versioning, so pin exact versions, read release notes and test before each upgrade. Budget both as recurring maintenance, not surprises.
- Hiring. The talent pools are similar in size: in the JetBrains 2024 survey, 38% of Python developers used FastAPI and 35% used Django, and many developers know both. Senior engineers who understand async Python, database performance and production operations take time to hire with either framework.
What it costs to migrate between them
Moving between Django and FastAPI after launch is rarely a simple swap, and most of the cost sits in the parts that are specific to each framework. Business logic written as plain Python functions and services moves easily. Validation rules move reasonably well, since DRF serializers and Pydantic models describe similar things. What does not move is the framework-specific layer: the Django admin has no FastAPI equivalent and must be rebuilt or replaced; Django authentication, sessions and permissions must be re-implemented; ORM queries must be rewritten for SQLAlchemy, along with their migrations history. Going the other way, from FastAPI to Django, means mapping SQLAlchemy models to Django models and adapting existing schema migrations.
That is why the cheaper path is usually not a full migration but an extraction: keep Django and add a FastAPI service for the workload that needs it, or keep FastAPI and add a small Django admin over the same database for operators. Before any migration, check these risks:
- How many screens and workflows depend on the Django admin today?
- Where are permissions enforced: in views, in the ORM layer or in templates?
- How much raw SQL or ORM-specific query code is there?
- Which authentication tokens and sessions do clients already hold?
- Is the migrations history clean enough to hand to another tool?
- Which endpoints actually need the change, and could they be extracted alone?
Common mistakes when choosing between Django and FastAPI
Most framework regrets come from a handful of avoidable mistakes:
- Choosing FastAPI and then rebuilding the Django admin by hand. If operators need to manage data, count the internal screens before you choose. Many teams discover six months in that they have written a worse admin panel.
- Making blocking calls in async endpoints. A synchronous database driver or HTTP client inside
async defstalls every request on that worker. Use async libraries, or declare the endpoint with plaindef. - Running async Django on WSGI. Async views under WSGI run in a one-off event loop and give you none of the concurrency. Deploy on ASGI if you rely on async.
- Expecting async transactions in Django. Transactions do not yet work in async mode. Plan to wrap transactional code in synchronous functions called through
sync_to_async(). - Not pinning FastAPI’s version. With 0.x versioning, upgrades can include changes that need attention. Pin exact versions and read the release notes.
- Leaving persistent connections on in async Django. Disable
CONN_MAX_AGEin async mode and use connection pooling, as the Django docs recommend. - Choosing on synthetic benchmarks. “Hello world” benchmarks measure an empty endpoint. Your real endpoints will spend their time in the database and in other services.
How YuSMP Group approaches the Django vs FastAPI decision
We don’t start with a favourite framework. Our process is the same for every new Python backend:
- Scope the workload. We estimate what share of the product is API, how much back office it needs, how many user roles there are, and whether AI or model serving is part of it.
- Prototype the heaviest endpoint. If one part is uncertain — a streaming LLM response, a high-volume ingestion endpoint, a complex query — we build that part first and measure it with realistic data.
- Choose and document the decision. The result is often a Django core with a FastAPI service for inference or high-concurrency work, but a single framework is the default for smaller teams.
If you want a second opinion on a new backend or an existing one, our Python and Django development and API development teams can review it with you.
Frequently asked questions
Is FastAPI better than Django in 2026?
Neither is better in general. FastAPI is the stronger choice for typed, async-first APIs, microservices and ML or LLM model serving. Django is the stronger choice for complete web applications with users, permissions, an admin panel and a relational data model. Decide by how much of your product is an API and how much is a full application, not by popularity.
Is FastAPI faster than Django?
For I/O-bound APIs, FastAPI on an ASGI server typically handles more concurrent requests per worker than synchronous Django on WSGI. The gap narrows when Django runs async views under ASGI. In most real products the database, query patterns and external calls limit throughput more than the framework, so profile your heaviest endpoint before choosing for speed.
Does Django support async now?
Yes, partly. Django supports async views and an async ORM interface through a-prefixed methods such as afirst(), acreate() and asave(). For real concurrency it must run under ASGI. Transactions do not yet work in async mode, so transactional code is wrapped with sync_to_async(), and persistent connections should be disabled in async mode in favour of connection pooling.
Can FastAPI replace Django?
For a pure API, yes. For a full application, only with extra work: FastAPI has no built-in ORM, migrations, user model or admin panel, so you assemble SQLAlchemy or SQLModel, Alembic and an authentication solution yourself, and build any back office by hand. If your product needs an admin and many user roles, Django usually remains the faster path.
Does FastAPI have an admin panel or ORM?
No. FastAPI focuses on the API layer: routing, validation with Pydantic, dependency injection and automatic OpenAPI docs at /docs and /redoc. For data access teams typically use SQLAlchemy or SQLModel with Alembic for migrations, and an admin interface has to come from a third-party package or be built separately.
Which is better for an MVP?
If the MVP needs operators to manage users, orders or content from day one, Django is usually faster because its admin, authentication and ORM replace weeks of custom work. If the MVP is an API behind a separate web or mobile front end, with no back office, FastAPI gets you to a documented, validated API quickly.
Which is better for machine learning and LLM APIs?
FastAPI is usually the better fit for the model-serving service itself: async endpoints suit slow model calls, streaming responses deliver tokens as they arrive, and Pydantic schemas give strict contracts for inputs and outputs. Django remains useful for the product around the model, such as accounts, billing, content and review screens.
Can I use Django and FastAPI in the same project?
Yes. A common pattern is a Django application that owns users, the admin and the core data, plus a FastAPI service for model inference or high-concurrency endpoints, connected by internal REST calls and a message queue. Decide early how authentication is shared and which side owns each table, to avoid two auth systems and duplicate models.
Is FastAPI production-ready if it is still version 0.x?
FastAPI is widely used in production, and its 0.x version number reflects the project's versioning policy rather than a lack of use. Its PyPI classifier is still Beta, so treat upgrades with care: pin exact versions, read the release notes and run your test suite before upgrading in production.
Should I use Django REST framework, Django Ninja or FastAPI for APIs?
If your API mostly exposes the same data your Django admin manages, stay inside Django: Django REST framework is the established choice with serializers and viewsets, while Django Ninja offers a FastAPI-like style with type hints and Pydantic-based schemas. Choose a separate FastAPI service when the API has a different workload or a different owning team.
Verdict: Django or FastAPI?
The right answer to Django vs FastAPI depends on what share of your product is an API and how much of it is a full application. Use these conditions as a starting point:
- Choose Django if people log in with different roles, operators need a back office, and the product is built around a relational data model. Add DRF or Django Ninja for the API.
- Choose FastAPI if the backend is mainly a typed API: model serving, microservices, a public API with a strict contract, or high-concurrency I/O behind a separate front end.
- Use both if you have a full product and a genuinely different workload next to it, such as LLM inference, and people to own each side.
- Stay with one if your team is small; two frameworks mean two upgrade schedules and two security surfaces.
Whichever you choose, start with a short workload analysis and a prototype of your heaviest endpoint. It costs little and turns a framework debate into a decision you can defend.