# Checkend > Open-source error tracking for coding agents. Checkend runs as one Cloudflare Worker with a D1 database in your own Cloudflare account, as one Node process with one SQLite file (for example in Docker), or as a hosted install. It is Sentry SDK compatible, and coding agents read its issues through an MCP server. Checkend is in early development. It receives errors from Sentry SDKs, groups them into issues, and gives them to coding agents through an MCP server (with issue briefs) and a JSON API. Each page below is plain Markdown. The diagrams of the HTML pages are described in text, and as Mermaid where it helps. ## Get started - [Overview](https://checkend.com/docs/index.md): Checkend is open-source error tracking for coding agents. It runs as one Cloudflare Worker with a D1 database in your own Cloudflare account, as one Node process with one SQLite file (for example in Docker), or as a hosted install. - [Quick start](https://checkend.com/docs/quick-start.md): This guide shows how to run Checkend, connect an app with a Sentry SDK, and read the errors. - [Web UI](https://checkend.com/docs/web-ui.md): Checkend has a small web UI for people: sign in with a passkey, connect your apps, and read the errors. Coding agents keep the MCP server and the API. - [Set up with an agent](https://checkend.com/docs/agent-setup.md): A coding agent can set up Checkend in your apps for you: register each app, add the SDK, send a test event, and connect itself with MCP. You give it a short-lived setup key, and you can follow its progress. - [The ce CLI](https://checkend.com/docs/cli.md): ce is the command-line interface of Checkend, for people, scripts and coding agents. It has two names: ce (short) and checkend. On a terminal, it prints short tables and cards. When its output is not a terminal (an agent, a script, a pipe), or with --json, it prints the API JSON. ## Agents - [MCP server](https://checkend.com/docs/mcp.md): Checkend has an MCP server, so that a coding agent can find production errors and read an issue brief: a short, structured summary of an issue that has what the agent needs to fix it. - [Verify fixes](https://checkend.com/docs/fix-loop.md): Checkend checks in production that a fix worked. An agent links its fix to the issue, your CI reports each deploy, and Checkend watches the error. When the error stops after the fix is deployed, the issue is verified. When the error comes back in a release that contains the fix, the issue is regressed. - [Webhooks](https://checkend.com/docs/webhooks.md): Checkend can call your URL when something happens to an issue: a new issue, a regression, or a verified fix. Each request is signed and has the issue brief, so that an agent runner can start work on the issue. - [Alerts](https://checkend.com/docs/alerts.md): Checkend can tell people about an issue in Slack, Discord, a GitHub issue or email: when an issue is new, regressed, verified, or has a spike of events. An alert is a webhook with another format. - [AI triage and similar issues](https://checkend.com/docs/ai-triage.md): Checkend can ask a Cloudflare Workers AI model to triage each issue: the likely cause, the severity, and whether the error is transient, noise, or a good task for an agent. It can also find similar issues. Both are advice only: Checkend shows them in the issue brief, and never acts on them. ## Ingest - [Send errors](https://checkend.com/docs/sending-errors.md): Checkend receives errors with the Sentry protocol. Checkend is Sentry SDK compatible: any Sentry SDK can send to a Checkend DSN. You do not need a special SDK. Without a Sentry SDK, use the native JSON endpoint. - [Source maps](https://checkend.com/docs/source-maps.md): The JavaScript that runs in a browser is usually minified: its stack frames point to lines like app.min.js:1:48213. Upload your source maps, and the issue brief shows the original file, line and source lines, so that an agent can find the cause. - [What Checkend stores](https://checkend.com/docs/what-checkend-stores.md): After Checkend accepts an event, it cleans the event, limits its size, and puts it in an issue. This guide tells what Checkend keeps, and what it removes. ## Reference - [API](https://checkend.com/docs/api.md): The Checkend API returns JSON. All endpoints start with /v1. - [Settings and health](https://checkend.com/docs/settings.md): The settings that you can change, budget mode for the Workers Free plan, and the health endpoint. ## Operate - [Run without Cloudflare](https://checkend.com/docs/self-host.md): Checkend can also run as one Node process with one SQLite file, for example in Docker. It has the same features and the same API as on Cloudflare. - [Backup and upgrade](https://checkend.com/docs/operations.md): In Docker Compose: ## Concepts - [Architecture](https://checkend.com/docs/architecture.md): Checkend is one Cloudflare Worker, written in TypeScript with Hono, and one D1 database. The core does not depend on Cloudflare, so the same code also runs on Node with SQLite (see Run without Cloudflare). ## Optional - [All docs in one file](https://checkend.com/llms-full.txt): every page above, in this order. - [Open specs](https://github.com/Checkend/checkend/tree/main/spec): the Agent Issue Brief (with a JSON Schema) and the fix verification protocol. - [Source code](https://github.com/Checkend/checkend): the Checkend repository. Coding agents: read AGENTS.md there first.