The AI Backend QA Engineer
Runs in every coding session against your running app and dependencies to catch real regressions and security issues your agent and code review tools miss.
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What engineering teams say about shipping with 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.
Your coding agent's tests carry the same blind spots as its code. Static review only catches the obvious, and manual checking doesn't scale. Slop piles up, draining engineering time and slowing releases.
The Backend Code Quality Platform
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.
Reviews the full impact of every code change so no issues slip through
Kerno maps the blast radius of a change and tests every path it touches.
| Assertion | Expected | Received |
|---|---|---|
| response status | 400 | 204 |
| tag row in database | 1 | 0 |
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 and verifies every code change, and evolves with your product
Kerno writes, runs, and updates your backend tests automatically, so your team catches real bugs without manual effort.
01Understand your product
Builds a graph of your codebase and docs, and maps every backend surface and the databases and other dependencies behind it.
02Build an exhaustive test suite
Creates hundreds of regression, integration, and security tests to capture how your backend works.
03Verify the full impact of changes
Surfaces the exact diffs against your baseline, so you see a change's full impact before it ships.
04Self-heal and evolve with your code
Retires stale scenarios and writes new ones as your product changes, so the baseline stays accurate.
- 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.
Functional API workflows
Verify endpoint behavior, multi-step request sequences, coordinated service interactions, and integration patterns.
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.
Full coverage in under a day
Install Kerno, get full test coverage, and roll out to your team without any friction. Set up once. Zero ongoing maintenance.
Install and calibrate
Point Kerno at your repo. It maps every endpoint, connects to your live services, and calibrates to how your backend runs.
Fully cover your backend
Kerno creates an extensive suite of baseline tests that capture how each API, task, and event behaves today.
Roll out to your team
The Kerno MCP connects to your agents, validating every code change and catching runtime issues 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?
Kerno verifies the full impact of every code change against your live stack. It covers your HTTP, gRPC, and GraphQL APIs along with your async tasks, message queues, and events, catching the functional, security, and edge-case bugs that only surface at runtime.
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, let it baseline your backend, and connect your team. You get full coverage in under a day, and Kerno keeps the suite current with zero ongoing maintenance.