Arbolus Intelligence

FastAPI

fastapi.tiangolo.com · Berlin Treptow, Germany

FastAPI is an open-source Python web framework for building high-performance APIs, designed to be easy to use while providing automatic data validation, interactive documentation, and asynchronous support. It is maintained primarily by its creator and contributors and is used by developers and organizations to build backend services and microservices. The project is free to use under an open-source license and is supported through sponsorships, donations, and related consulting or training activities rather than traditional product revenue.

  • API Management & Integration
  • No-Code & Low-Code Platforms
Listed in
Revenue
$200.0K
Employees
5
Founded
2018
Headquarters
Berlin Treptow, Germany

What 11 Arbolus experts think of FastAPI

NPS scores are highly positive with NPS ranging from 8 to 10 from all experts. Renewal intent is strong among enterprise and influencer roles, though some larger spenders indicate uncertainty due to ecosystem considerations. Stickiness is highest among users with over 1 year of implementation, and expert qualitative feedback praises development efficiency, async support, and clear documentation. Concerns primarily center on limited ecosystem for larger production deployments and dependency on core maintainers.Overall Customer Sentiment: Positive

Who reviewed FastAPI

Total customers 11 11 current · 0 former
Reviews growth +11 in six months
Seniority of respondents
  • C-Suite 50% (6)
  • Director 20% (2)
  • Manager 30% (3)
Engineering Engineer C-Suite NPS 8 Submitted Sep 2026
Engineering Executive Director NPS 10 Will renew Submitted Jul 2026
Engineering Engineer Not specified NPS 10 Submitted Sep 2026

Employer names and spend open in the full report, along with the other 8 customers.

Everything 11 customers told us about FastAPI.

Employer names, spend, renewal intent and every written answer behind the numbers on this page.

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Sentiment

72 Net Promoter Score, from 11 scored reviews
  • Promoters 8
  • Passives 3
  • Detractors 0

Cumulative NPS by month

-1 over 4 months
  • Jun 10
  • Jul 9
  • Aug 9
  • Sep 9

Net Promoter Score across 1 reviews, accumulated up to each month. Category median 72 across 1 companies.

Praised

  • Automatic Documentation and Type Safety
  • Development Efficiency
  • Strong Performance and Async Support
  • AI and Automated Migration Support

Criticised

  • Limited Built-in Features
  • Async Pitfalls
  • Maintainer Concentration and Support Latency
  • Limited Contributor Pool

What customers say

Automatic Documentation and Type Safety
“The main reason I use FastAPI is that type hints give me validation and OpenAPI docs without duplication, helping internal service integration and onboarding.”
Development Efficiency
“I rely on FastAPI for building Python-based APIs and backend services efficiently, supporting rapid development and clear API structures.”
Strong Performance and Async Support
“I value FastAPI’s built-in async support and the fact that it gets out of the way, making onboarding easy and new hires productive right away.”

Renewal intent

Plan to renew 75%
  • Will renew 3
  • Undecided 1
  • Not renewing 0

Plan to renew, by seniority

  • C-Suite 100% 1 answer
  • Director 50% 2 answers
  • Manager 100% 1 answer
  • 10/10 Average score from customers who will renew
  • 8/10 Average score from undecided customers

Report

Customer Report - Sep 2026 Sep 2026 11 + 1

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