Y Combinator W25
YC Winter 2025 developer tools companies
The Javascript framework for building AI agents, from the Gatsby devs
30 people · San Francisco, CA, USA · Developer Tools, Open Source, AI · YC page
Stablecoin API for global payments
9 people · San Francisco, CA, USA · Developer Tools, Fintech, Crypto / Web3, Payments · YC page
The LLM Eval and Observability Platform for AI Quality
7 people · San Francisco, CA, USA · Developer Tools, Generative AI, Open Source, AI · YC page
connect, migrate and implement enterprise systems
6 people · BY, Germany · Open Source, API, Enterprise, Enterprise Software · YC page
Reasoning Fine-Tuning
6 people · San Francisco, CA, USA · Developer Tools, Generative AI, Reinforcement Learning · YC page
An AI teammate that automatically updates your customer-facing docs
5 people · San Francisco, CA, USA · Developer Tools, Generative AI, AI · YC page
Global B2B Stablecoin Processor
4 people · San Francisco, CA, USA · Developer Tools, Payments, Compliance · YC page
The Developer tool for Designers
4 people · San Francisco, CA, USA · Developer Tools, Design, Design Tools, AI · YC page
We make mobile apps using AI.
3 people · San Francisco, CA, USA · Developer Tools, Generative AI, Design, AI · YC page
Open Source React.js Library for AI Chat
3 people · San Francisco, CA, USA · Developer Tools, Generative AI, Chat, Web Development · YC page
PCB component librarian
3 people · Zürich, ZH, Switzerland · AIOps, Electronics, AI · YC page
Continuous inference for streaming AI models
2 people · Paris, Île-de-France, France · Generative AI, Infrastructure · YC page
Agent identity and communication infrastructure
2 people · London, England, United Kingdom · Developer Tools, Email, Infrastructure, AI · YC page
The fastest native app for agentic engineering.
2 people · San Francisco, CA, USA · Developer Tools, Open Source, AI · YC page
OpenRouter for Integrations
2 people · New York City, NY, USA · Developer Tools, Workflow Automation, Open Source, Personalization · YC page
AWS for AI Agents
2 people · San Francisco, CA, USA · Developer Tools, Generative AI, Infrastructure, AI · YC page
Building agents that reads logs and fixes issues on your behalf.
2 people · San Francisco, CA, USA · Infrastructure, AI · YC page
The agentic AI Word editor
2 people · San Francisco, CA, USA · Consumer, AI, Databases · YC page
AI documentation engineer – test & autoimprove stale product docs
2 people · San Francisco, CA, USA · Developer Tools, API, Automation, AI · YC page
We turn complex API integrations into drop‑in full‑stack libraries
2 people · Amsterdam, NH, Netherlands · Developer Tools, API, Infrastructure, Databases · YC page
Reimagining how Machines Learn
San Francisco, CA, USA · AIOps, Developer Tools, Automation, AI · YC page
Vercel For GPUs
3 people · San Francisco, CA, USA · AIOps, Developer Tools, DevOps, Cloud Computing · YC page
Daily productivity tracker
2 people · San Francisco, CA, USA · Developer Tools, Open Source, Infrastructure, AI · YC page
FAQ
How many developer tools companies are in YC Winter 2025 (W25)?+
23 launched companies in YC Winter 2025 carry a developer-tools or infrastructure tag in YC's directory (snapshot of 2026-10-20); 21 are active. Companies that have not launched publicly on YC's site yet are not counted.
What are the top tags in YC W25 dev tools?+
Developer Tools (18), AI (15), Generative AI (7), Infrastructure (6), Open Source (6). 6 of 23 are tagged open source.
Which YC W25 dev-tool companies are the largest?+
By team size on YC's directory: Mastra, BlindPay, Confident AI.
← Spring 2025Fall 2024 →All YC dev-tool companiesOpen-source YC companies
Source: Y Combinator's public company directory via the unofficial mirror yc-oss/api. DevHunt is not affiliated with Y Combinator.