FastAPI Development for US Startups & SMBs
We build high-performance, async FastAPI APIs, microservices, and the AI service backends modern products run on. AI-assisted engineering gets a production API in your hands in weeks, not months, with senior engineers you talk to directly and full ownership of all code and IP.
What We Build with FastAPI
From a first production API to the AI service layer behind your product, across the async patterns and tooling US teams ship on.
High-Performance REST & Async APIs
Type-safe, async APIs that hit Node- and Go-level throughput in Python, built OpenAPI-first with automatic, always-accurate docs.
- FastAPI & Pydantic v2
- Async I/O & OpenAPI-first
- Auto-generated interactive docs
AI & LLM Service Backends
FastAPI is the default service layer for AI. We ship RAG endpoints, model-serving APIs, streaming responses, and agent backends.
- RAG & vector search endpoints
- LLM streaming (SSE) responses
- AI agent & inference APIs
Microservices & Event-Driven Systems
Decoupled, independently deployable services with message queues and clean contracts, sized to scale the parts that actually need it.
- Service boundaries & contracts
- Celery / queues & workers
- Docker & Kubernetes ready
API Migration & Modernization
Move slow or aging Flask, Django REST, or legacy APIs to FastAPI, for real async performance gains without a risky big-bang rewrite.
- Flask / DRF → FastAPI
- Performance & async audit
- Incremental, zero-downtime cutover
Real-Time & Streaming APIs
WebSocket and server-sent-event services for chat, live dashboards, and AI streaming, built to hold many concurrent connections.
- WebSockets & SSE
- High-concurrency connections
- Live data & notifications
Integrations & Backend-for-Frontend
A clean API layer between your React or mobile front end and the services, payments, CRMs, and third-party APIs behind it.
- Stripe, payments & webhooks
- BFF for React & mobile
- Salesforce & REST integrations
FastAPI, Django REST, or Flask? How to Choose
The three frameworks solve different problems, and real products often mix them. Here's the honest version, so you pick the right tool instead of the trendy one. We help you make the call in discovery, before any budget is committed.
Choose FastAPI when…
- You need a high-performance, type-safe API or microservice
- You're serving AI/LLM features, RAG endpoints, or heavy async I/O
- OpenAPI-first contracts and Pydantic validation are priorities
- You want a lightweight service rather than a full web framework
Choose Django REST when…
- You want a full web app (admin, auth, and ORM) plus its API
- You're building a SaaS, portal, or content-driven product
- Convention-over-configuration and a large ecosystem matter most
- Raw async throughput is not the dominant constraint
Choose Flask when…
- You have a small, simple service with minimal dependencies
- You want maximum freedom over structure and libraries
- Async and built-in validation are not requirements
- You are maintaining an existing Flask codebase, not starting fresh
How We Start: Fixed Scope, Fast
We don't lead with open-ended retainers or an hourly meter. Every engagement starts with a focused, fixed-scope sprint, so you get a clear deliverable and a real estimate before any long-term commitment.
API Discovery Sprint
- API design & service architecture
- FastAPI vs. DRF vs. Flask decision
- Timeline & fixed estimate
API / Microservice Build
- Production FastAPI service or platform
- Auth, data model & integrations
- Deployed, documented & load-tested
Migration & Performance Audit
- Flask / DRF / legacy API audit
- Async & performance fixes
- FastAPI migration roadmap
Every engagement starts with a fixed-scope sprint and a clear deliverable. You get a concrete estimate before any long-term commitment.
Why US Teams Choose MicroPyramid
You're not hiring a 500-person body shop with a rotating bench. You get a focused, senior Python team that ships APIs built to last.
AI-Native API Layer
FastAPI is where AI features live. We build RAG, streaming, and agent backends directly into your API, not bolted on as a separate system.
Senior Engineers, Direct
You work with the people writing the code, not account managers or a rotating bench of juniors handed your project.
You Own Code & IP
Full source code, IP, and infrastructure are yours from day one. We sign NDAs and IP-assignment before work begins.
US Time-Zone Overlap
Daily overlap with ET/PT for standups, demos, and reviews. Async-friendly, but reachable when you need a real conversation.
How We Build Your API
A proven four-stage process with weekly demos and senior review, so you always know exactly where your project stands.
Discovery & Scope
API contracts, data model, framework decision, and a fixed estimate before a line of code is written.
Architecture & Design
Service boundaries, OpenAPI schema, and the infrastructure your API will run on, agreed up front.
AI-Assisted Build
Sprint-based development with weekly demos, CI/CD, automated tests, and senior review on every change.
Deploy & Support
Production deployment on AWS or GCP, load testing, monitoring, and ongoing iteration after launch.
The FastAPI Stack We Build On
Current, well-supported tools across the framework, async data layer, AI services, and the cloud your API runs on.
Framework
Data & Async
AI & APIs
Cloud & DevOps
Proof, Not Just Promises
12+ years building Python software, 50+ projects delivered, and long-term clients who keep coming back.
"MicroPyramid is a great place to go to if you are looking for passion as an ingredient for your enterprise or project. They understand the future, and the craft of manifesting your vision. In our case they actually made one of our dreams come to life."
"They are our valued development partners specifically because they have a passion for inclusive finance that cannot be matched by most development houses. They are competent with unique ideas and thorough in their process."
NOW Finance
Leading Australian non-bank lender providing simple, data-driven personal loans
CREDITABLE
Employee financial wellness platform for savings, loans, and workplace finance
Bough Digital
UK-based digital marketing agency with tailored marketing campaigns
Refactored
Learning management system for Python tutorials, exercises, and assessments
FastAPI Development FAQs
Straight answers to what US founders and CTOs ask us before starting a FastAPI project.
What drives the cost of FastAPI development?
The main drivers are scope and endpoint count, the complexity of your data model, the number of integrations and external services, whether you need real-time or streaming features, and any compliance or security requirements. A focused API or microservice costs far less than a production API platform, which in turn costs less than a large multi-service or enterprise system. We give a fixed estimate after a short discovery sprint rather than an open-ended hourly meter.
How do you keep costs efficient?
We run senior-only teams with no junior bench, so you are not paying people to learn on your project. We use AI-assisted engineering across coding, testing, and review, which reaches the same outcome in fewer hours, and we work in fixed-scope sprints with a clear deliverable. You own all code and IP from day one.
How long does it take to build a FastAPI API?
We ship a production FastAPI service in roughly 3-6 weeks and larger multi-service platforms in a couple of months, faster than traditional agencies because we use AI-assisted engineering across coding, testing, and review, with senior oversight on every change.
FastAPI vs Django: which should I use?
Choose FastAPI for high-performance, type-safe APIs, microservices, and AI/LLM or RAG service layers where async I/O and OpenAPI-first contracts matter. Choose Django (with Django REST Framework) for full web apps and SaaS that need admin, auth, and an ORM out of the box. Many products use both: Django for the app, FastAPI for the AI and high-throughput services. We help you decide in discovery, before any cost is committed.
Is FastAPI fast enough compared to Node.js or Go?
For most API workloads, yes. FastAPI runs on async Starlette and Uvicorn and delivers throughput in the same class as Node.js and close to Go for typical I/O-bound APIs, while keeping Python’s ecosystem for data and AI. Go still wins for extreme CPU-bound or ultra-low-latency cases, but for AI service layers, data-heavy APIs, and most SaaS backends, FastAPI is fast enough and far quicker to build.
Why is FastAPI the standard for AI and LLM backends?
FastAPI is async by design, so it handles the long-lived, concurrent connections that LLM calls and streaming responses require, and it sits in Python, the native language of AI tooling like LangChain, vector databases, and model SDKs. That makes it the natural place to build RAG endpoints, model-serving APIs, streaming chat, and agent backends without a separate stack.
Can you migrate our Flask or Django REST API to FastAPI?
Yes. We audit the existing API, identify async and performance bottlenecks, and migrate to FastAPI incrementally, running services side by side and cutting over endpoints without downtime, rather than risking a big-bang rewrite. Many engagements start as a migration and performance audit sprint.
Do you work with US companies and what about time zones?
Yes, most of our clients are US-based startups and SMBs. We keep several hours of daily overlap with US time zones (ET/PT) for standups, demos, and reviews, and you work directly with the senior engineers building your API.
Building an AI feature or RAG backend?
FastAPI is the service layer we build AI on: RAG endpoints, model serving, streaming chat, and agents. See how we add AI and knowledge systems to your product.
Explore Related Services
Specialized engineering teams for the stacks and platforms your product depends on.
Ready to Build Your FastAPI Project?
Book a free discovery call. We'll talk through your idea, recommend the right framework and architecture, and give you a fixed scope and estimate, no obligation.