Backend API Development in Go and Python (FastAPI, Flask)
I build backend APIs in Go or Python: documented endpoints, authentication, background jobs, tests and a Docker image ready to deploy. It’s for startups and agencies that need a reliable service behind their app. From $1,300 ($1,000 founding) for up to 10 endpoints, about 3–4 weeks. Email me what the API must do.
See a sample report, proposal and weekly update- Price
- from $1,300
- Founding
- from $1,000
- Timeline
- 3–4 weeks
- Format
- Fixed scope, fixed price
- Hours
- US Eastern Time, async
Who this is for.
A good fit if
- Startups needing an API for a web or mobile app someone else builds
- Teams that need a service for one hard job: webhooks, entitlements, file processing, a worker
- Agencies that need a backend for a front end they already made
Common triggers
- A mobile or front-end team is blocked waiting for an API
- A PHP monolith needs one fast, separate service
- A script that runs “on someone’s laptop” has to become a real service
Not a fit if
- You need Django, Node.js or Java specifically
- You need hard real-time guarantees, clustering or Kubernetes
- There’s no one who can decide what the API should return
What I do, and what you get.
What I do
- Write the API contract first (an OpenAPI document) and agree it with you
- Build endpoints with validation, auth (API keys, JWT or sessions) and consistent errors
- Add background jobs (Go workers, Celery) and database migrations
- Write tests: unit tests for logic, HTTP tests for every endpoint
- Package it as a small Docker image with health checks and config by environment variables
- Add metrics for the parts that matter (request counts, job failures)
What you get
- Source code in your repository, with tests running in CI
- An OpenAPI document and a short developer guide
- A Docker image and a Compose file for local and single-server runs
- A runbook: configure, deploy, migrate, roll back
- Handover notes and a 14-day fix window
Your part
- Decisions on the API contract
- The database choice, or acceptance of mine (PostgreSQL)
- Hosting and container registry accounts
- Third-party API keys
Included
- Endpoints, auth, validation, jobs and tests
- OpenAPI document and developer guide
- Docker image, Compose file and CI
- Metrics for key paths
Not included
- Front end or mobile app
- Load testing (quoted as a Plus add-on)
- Kubernetes, multi-region and 24/7 support
- A public developer portal (see Developer Docs)
Fixed prices, agreed before work starts.
Up to 10 endpoints, auth, tests and a Docker image.
Up to 25 endpoints, background jobs, webhooks and metrics. 2 monthly milestones of $1,300 ($1,000 founding).
Multiple services or a worker fleet, signed tokens, an audit log and deeper security work. 4 monthly milestones of about $1,140 ($875 founding).
Build your scope
- Timeline
- 3–4 weeks
- Payment
- 50% to start ($650), 50% before handover
- Earliest start
- Oct 5
Founding price: 3 of 7 spots left, until Mar 31, 2027 — one-off work, in return for a testimonial. How it works
Prices are in USD, paid by bank transfer against an invoice. Work under $1,000 is paid upfront; larger work is 50% to start and 50% before handover, or monthly milestones. How working together works
Variations
- Go (Echo or standard library)
- Long-running services, websockets, high concurrency and a single static binary.
- FastAPI + Celery
- Python data work, AI calls, spreadsheets and files.
- Flask
- Small internal services or agents on a server.
- Existing API
- New endpoints added to your service in its current style.
How it runs.
- 01
Brief
You tell me what the API serves and to whom.
- 02
Contract for approval
I draft the OpenAPI contract and you approve it.
- 03
Build with tests
I build it with tests and send written progress every week.
- 04
Deploy to staging
I deploy it to your staging environment.
- 05
Handover
You get the handover pack and a 14-day fix window.
Where I have done this before.
Licensing & Entitlement Platform
31k lines of Go in production, 654 Go tests, and signed licenses that verify offline.
Read the case study →Infrastructure · Go · Remote executionCentralized Fleet Control
Go WebSocket relay and agent where every command gets an answer.
Read the case study →Multimodal AI · Auction catalogingAI Cataloging System for Fine-Jewelry Auctions
FastAPI + Celery with per-item progress on background jobs.
Read the case study →Questions buyers ask.
Go or Python?
Go for long-running, concurrent services; Python when the work is data, files or AI libraries. I’ll recommend one in the scope.
Will my front-end developer be able to use it?
Yes. The contract comes first, with examples for each endpoint.
Do you host it?
It runs in your account. I can set up the server as a separate service.
What about security?
Validation, auth, rate limits and secrets outside the code are standard. This is not a pen test.
Can you take over an existing Go or FastAPI service?
Yes, after a short code read.
Ask about Backend APIs.
Tell me what you have and where it hurts. I reply within one US business day with either a fixed quote or the entry step that makes a fixed quote possible.
Helpful to include
- What the API serves and to whom
- A rough endpoint list
- Auth needs
- Data volumes
- Language preference
- Hosting
- Deadline
- Budget
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