

Kerno automatically orchestrates your app and its dependencies locally and mocks external dependencies so your tests run against the same stack your code runs on.

"Kerno was up and running in minutes with no manual work, and it made our API migration so much smoother. We could instantly validate that every change made by Cursor worked the way we expected, and now it's a core part of how we build."
Kerno captures the baseline behavior of critical paths for your REST endpoints, then compares your code changes to the baseline and flags diffs.
As your app evolves, Kerno retires stale tests and generates coverage for new behavior automatically. You'll never manually maintain a test suite again.

"Kerno saves us a lot of manual work and helps us catch side effects and issues that would definitely break our projects' backends. Our engineering team loves it."
"We were using Cursor heavily and had no real safety net. Kerno was running in minutes, and suddenly we could move fast without that low-level anxiety every time an agent touched something critical. It's now a non-negotiable part of our stack."
Fewer breaking changes reaching production
Faster feedback. No more waiting on CI
Saved per developer each week fixing issues post-merge
Reduced token consumption using Kerno index tools
Kerno is a local CI that lets your AI coding agent validate its changes against your real backend stack and fix what it broke, in context, in every session.
It indexes your codebase, spins up your real infrastructure locally in Docker, generates integration tests against your API endpoints, and validates that code changes don't break existing behavior.
When something breaks, your agent gets the debug context to fix it in the same session, so you ship code that works as part of your system.
Kerno tests against your real stack, not mocks. It spins up your actual databases, queues, and caches locally in Docker, and mocks only third-party external services. It uses deterministic SCIP indexing to know exactly what your code change affects, so it runs only the relevant tests. And it generates, maintains, and retires tests automatically as your code evolves, with no manual upkeep.
No. Kerno automatically generates test scenarios for every discovered HTTP endpoint. Scenarios cover functional workflows, contract validation, error handling, authentication, and edge cases. As your code evolves, Kerno adds scenarios for new endpoints and retires scenarios for removed ones.
Kerno works with any AI coding tool that supports MCP (Model Context Protocol). Claude Code, Cursor, Windsurf, and Codex CLI are verified setups. Kerno exposes MCP tools that let your agent start environments, capture baselines, and validate changes directly.
Kerno currently supports TypeScript, Python, and JavaScript. We're actively working on expanding support to all major backend languages. Performance varies by language based on available training data.
Docker (installed and running), Node.js 18 or later, and Git. Your project must be a Git repository. Install the CLI with npm i @kerno/cli, then run kerno mcp in your project directory.
Your code never leaves your machine. We maintain a zero-day retention policy with service providers, ensuring your code remains completely private.
We only use public data to train our system. Your private code is strictly off-limits and will never be used for training purposes.
Kerno offers free usage for qualified Open Source Projects and a significant discounts for pre-Series A startups. Drop us a note to check your availability.