Verify & secure everything
your agents ship.
Kerno independently tests your critical flows locally against your real stack. Catch runtime and security bugs inside the agent loop before they merge.
Agents and engineers at these companies use Kerno.
“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.”
“Using Kerno with Claude Code has been a game changer. You get quick feedback with no manual effort, and it saves you a lot of time and hassle debugging integration issues post-merge.”
“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.”
“Regressions have always been a huge bottleneck for our team. Kerno has been a force multiplier helping us ship releases much faster without the manual overhead of QA.”
Slow feedback loops are killing your engineering velocity
The bottleneck isn't writing code. It's proving it works at runtime. Independent verification needs to happen inside the agent loop, not hours later in CI, where slop piles up, draining engineering time, forcing expensive rework and slowing releases.
The Runtime Quality & Security layer for your backend
Give every developer and agent staff-level testing knowledge to catch the expensive runtime issues DIY testing and code review miss, right at the source.
Verify every code change against your live stack & dependencies
Kerno catches the functional and security bugs that only surface at runtime, before they ship.
Verifies every critical flow a code change touches
Kerno maps a change's blast radius and verifies each flow end to end.
Bring the same high quality verification loop to every engineer
Kerno gives coding agents structured signals and persistent code context on every change.
Kerno tests your critical flows end to end, and keeps up with your product
Kerno writes and runs tests for your critical user flows and every entry point behind them, so your team catches real bugs at the source before they ship.
01Understand your product
Builds a graph of your codebase and docs, maps every entry point and the dependencies behind it, and maps your critical user flows with you.
02Test your critical flows end to end
Tests each user flow as one journey across your APIs, then covers every entry point behind it in depth.
03Verify the full impact of changes
Re-runs every flow a change touches and shows the step that broke, with the outcome the user expected and what actually happened.
04Self-heal and evolve with your code
Updates entry-point tests as your product changes and re-generates flows when behavior changes on purpose.
- TypeScript
- JavaScript
- Python
- Java
- Go
- Rust
- C#
- C
- Kotlin
- Ruby
- PHP
- PostgreSQL
- MySQL
- MariaDB
- MongoDB
- ClickHouse
- Redis
- Kafka
- RabbitMQ
- AWS
- Azure
- Google Cloud
Catches the bugs that only appear at runtime
Static review reads your code and unit tests run on mocks. Kerno catches the functional, security, and edge-case bugs that only surface at runtime.
End-to-end user flows
Verify complete user journeys across your APIs, from the first request to the outcome read back from your system.
Contract & schema validation
Validate request and response structures, data types, required fields, serialization rules, and version compatibility.
Authorization & authentication
Review token validation, role-based access rules, permission scopes, session handling, and all credential-related flows.
Error handling & resilience
Validate status codes, error body formats, retry behavior, backoff procedures, timeout handling, and controlled fallbacks.
Boundary & edge cases
Validate payload size limits, pagination behavior, null or empty values, malformed inputs, and constraint-based validation.
Security · OWASP Top 10
Validate broken object- and function-level authorization, injection, excessive data exposure, mass assignment, and SSRF.
MCP server testing
Verify each tool your MCP server exposes, including returned content, structured output, schema conformance, and error handling.
AI agent testingComing soon
Verify how your agent calls tools, chains model steps, and handles streaming responses, with OpenAI, Anthropic, and others mocked for deterministic runs.
Kerno learns your business and standards
It learns your domain logic, your conventions, and your standards, then applies them on every change.
Define custom rules
Give Kerno your standards and business rules in plain English, scoped to the repos and paths you choose. It applies them on every run.
Learns from your feedback
Kerno learns from every test run and the feedback you give it, building a sharper model of your codebase and standards over time.
Your critical flows covered in under a day
Install Kerno, map your critical flows, and roll out to your team without any friction. Set up once.
Install, calibrate and map your flows
Point Kerno at your repo. It maps every entry point, connects to your running app and its dependencies, and maps your critical user flows with you.
Cover your critical flows
Kerno tests each critical flow end to end and builds baseline tests for every API, task and event behind it.
Roll out to your team
The Kerno MCP connects to your agents, validating every code change and re-running the flows it touches before they reach production.
FAQs
Got any extra questions? Reach out on our community channel and we'll be happy to help.
What does Kerno actually test?
Your critical user flows, end to end, against your live stack. Kerno also tests every entry point behind them, including HTTP APIs, MCP tools, background tasks and message queues, catching the functional, security and edge-case bugs that only surface at runtime.
What is a user flow?
One thing a person does with your product, like signing up or checking out, tested as one journey across every API call it takes. Kerno maps your critical flows with you and checks that the outcome really happened in your system.
How is this different from unit tests or static analysis?
Static review reads your code and unit tests run on mocks. Kerno runs your actual code against your live stack and real dependencies, so it catches runtime behavior that neither one can see.
Does Kerno run against my real stack?
Yes. Kerno connects to the services and datastores you already run, including PostgreSQL, MySQL, MongoDB, Redis, Kafka, and more, and manages the data layer so it can exercise them the way your application does.
Is my code safe?
Kerno encrypts everything end to end and never retains your code, and a SOC 2 Type 2 audit is in progress. Your private code is never stored or used for training.
Which coding agents does Kerno work with?
Kerno connects over MCP to any coding agent, including Claude Code, Codex, Cursor, GitHub Copilot, and more. Your whole team validates every change from the agent they already use.
How long does it take to get started?
About an afternoon. Install Kerno, map your critical flows, let it baseline your entry points, and connect your team. You get full coverage in under a day.