APIs Jobs - December 2025

VC-backed, post–Series A startup building data replication and transform platform. Hiring Head of Applications Engineering to own strategy, people, delivery, SLOs across Applications stack, partner with CTO, improve engineering org and incident response, and …

When you npm install openai or pip install anthropic, you’re pulling code generated by Stainless. We’re building the platform for high-quality, easy-to-use APIs — and companies like OpenAI, Anthropic, and Cloudflare already rely on us. We’re ~3 years old, ~50…

CEF AI builds an AI-first data automation platform for secure, decentralized orchestration of agents that compute directly on encrypted data streams. Small team, high ownership, low bureaucracy. Responsibilities: AI Innovator: prototype and ship production AI…

Automat (runautomat.com) | San Francisco (In Person) | Multiple Roles. Automat (YC W23) - the simplest way for companies to create AI agents that take on repetitive, tedious tasks — from navigating complex user interfaces to reading and processing documents. …

At Float, we're building capital markets infrastructure. Our AI-native platform is tackling decades-old inefficiencies, creating technology that enables financial institutions to interact seamlessly and automate intelligently. Based in SoHo, New York and back…

Ionworks builds battery simulation and optimization software used by R&D teams designing next-generation batteries. Seeking a founding backend/systems engineer to own large pieces of the backend and help scale from early customers to broader industry use. Wor…