Captures failed Cloudflare Workers requests and D1/KV/R2/Workers AI binding reads into replay files, and provides MCP tools to inspect crashes and replay handlers with deterministic mocked bindings.
Exports captured Cloudflare Worker crashes as Vitest regression tests, with dry-run or write options.
Click on "Deploy Server".
Wait a few minutes for the server to deploy. Once ready, it will show a "Started" state.
In the chat, type @ followed by the MCP server name and your instructions, e.g., "@flaredump replay ./crash.cfreplay.json and show the failing request"
That's it! The server will respond to your query, and you can continue using it as needed.
Here is a step-by-step guide with screenshots.
Flight recorder for Cloudflare Workers: capture failed requests (D1, KV, R2, and Workers AI reads) into .cfreplay.json and replay them offline in milliseconds.
bunx flaredump replay ./crash.cfreplay.json
npx flaredump replay ./crash.cfreplay.json
# or install in your project / globally
bun add -d flaredump
npm i -D flaredumpJSR:
bunx jsr add @kanchingyg/flaredump
npx jsr add @kanchingyg/flaredumpRelated MCP server: FlowLens MCP
npx flaredump replay ./crash.cfreplay.json
bunx flaredump replay ./crash.cfreplay.json
npx flaredump --explain ./crash.cfreplay.json --model ollama/qwen2.5-coder:7b
npx flaredump --mcpimport { withFlareDump } from "flaredump";
export default withFlareDump(async (request, env) => {
const rows = await env.DB.prepare("SELECT 1").all();
return Response.json(rows);
});On throw or status >= 500, flaredump serializes the request plus binding results (secrets redacted as [REDACTED]).
Add to your MCP config:
{
"mcpServers": {
"flaredump": {
"command": "npx",
"args": ["-y", "flaredump", "--mcp"]
}
}
}Tool | Purpose |
| Request, stack, D1/KV trace (context-truncated for local models) |
| Re-run handler with deterministic mocked bindings |
| Emit a Vitest regression test ( |
Use --explain with any OpenAI-compatible or Ollama endpoint to summarize a capture:
npx flaredump --explain crash.cfreplay.json --model ollama/qwen2.5-coder:7bThis server cannot be deployed
Production bugs with replay, network, console and stack, ranked for your coding agent to fix.
Build, validate and deploy workflows as Cloudflare Workers in your own account, with approval.
Discover Playwright workflows, start runs, and inspect results in Playrunner Cloud.
Debug webhooks from your AI agent: inspect and replay captured webhooks on localhost.
