Treevoxa offers FastAPI development services for teams that want a Python back end that is fast, typed and documented from the first endpoint. We build APIs and web back ends with FastAPI on PostgreSQL, and we run one in production ourselves: the back end of DealWisp, our branded offers product.
FastAPI backend development we offer
- New APIs for web and mobile apps, partners and internal tools.
- SaaS back ends: accounts, tenants, roles, subscriptions and admin endpoints.
- Integrations with payment providers, file storage, email services and AI models.
- Migrations from Flask or older Python services to FastAPI.
- Audits and rescues for FastAPI projects that have grown hard to change.
FastAPI in production: DealWisp
DealWisp's API is a FastAPI application served by Uvicorn. It talks to PostgreSQL through asyncpg, validates every request with Pydantic models, hashes passwords with bcrypt, signs users in with JSON Web Tokens, processes images with Pillow, stores files on Amazon S3 through boto3, and sends transactional email. Its dependencies are pinned and trimmed to what the code actually imports, and a pytest suite, run in parallel, covers the API. That is the standard we bring to client projects.
FastAPI web development: how we build
- Contract first. Pydantic models for every request and response, agreed before the handlers are written. FastAPI turns them into OpenAPI documentation your front-end team can use on day one.
- Async where it pays. Database and network calls are asynchronous, so one server handles many requests at once.
- Security built in. Token authentication, role checks on every route, rate limits and validated input.
- Tests with the code. Every endpoint, including the failure cases.
- Containers. A Docker image and environment configuration, so it deploys the same way everywhere.
Tech stack for FastAPI projects
| Part | What we use |
|---|---|
| Framework | FastAPI, Starlette, Uvicorn |
| Validation | Pydantic, email validation |
| Data | PostgreSQL, asyncpg, SQL migrations |
| Security | JWT, bcrypt, role-based access |
| Services | Amazon S3 (boto3), transactional email, image processing |
| Testing | pytest, pytest-xdist |
Technologies related to FastAPI
FastAPI is one of the Python frameworks we use; see Python development services for the wider picture and Django development services for data-heavy back offices. For API design in general, see API development services.
Engagement models for FastAPI work
- Fixed scope for a defined API or service.
- Dedicated FastAPI developer working only on your product, billed monthly. See hire dedicated developers.
- Hourly for audits, fixes and small changes.
What FastAPI development costs
The cost of a FastAPI back end depends on the number of endpoints and data models, the integrations, data migration and the testing you need. Our custom software development cost guide explains how quotes are built, and software developer hourly rates compares what teams charge. We quote in US dollars, in writing.
Who FastAPI development is for
- Startups and product teams that want a fast, typed back end for a web or mobile app.
- Data and machine-learning teams whose models are written in Python and need a reliable API around them.
- Companies on Flask or older Python services that want typed validation and automatic documentation.
- Businesses integrating AI models that need a Python service to call them safely, with limits and logs.
FastAPI pitfalls we avoid
- Blocking calls inside async code, which quietly stall every request. Database and network calls stay asynchronous end to end.
- Models that drift from the database. Request and response models are kept separate from storage, so a schema change does not leak into the API.
- Missing permissions. Authentication is not authorisation; every route checks the user's role, not only that they are signed in.
- Unpinned dependencies. Versions are pinned and trimmed to what the code imports, as in DealWisp, so a fresh install builds the same way every time.
What to send us for a FastAPI quote
What the API must do, who will call it, expected traffic, the data it stores, and any existing code or API documentation.
Questions to ask before you hire a FastAPI team
- Can we see a FastAPI service you run in production?
- How do you keep request models separate from the database?
- How do you handle blocking work inside async code?
- What does your test suite cover, and does it run on every change?
- How are permissions checked on each route?
Ask every bidder the same questions, in writing, and compare the answers before you compare the prices.
Working across time zones on FastAPI projects
We work remotely with a daily overlap window in your working hours, agreed before the project starts, for reviews and decisions; the build continues around it.