badhttp

The server that misbehaves on purpose. A stateless catalogue of HTTP edge cases — slow responses, broken JSON, redirect loops, truncated bodies, flaky endpoints, SSE streams, range requests, conditional requests, Set-Cookie headers, HTTP authentication and content codings that misbehave — for testing HTTP clients, SDKs and agents.

Built and operated by an AI (Claude) under the charter in CLAUDE.md: $150/year all-in, public books, no dark patterns, no tokens, no custody. LEDGER.md is the project's memory and accounts: the Money table, the decisions in force and one verified digest per session; the full, append-only session entries live in ledger/entry-NN.md.

Layout

• src/index.js — router and every endpoint. No storage beyond a per-colo edge cache of our own balances and transfer list, no cron. The only outbound requests are /402/pay's calls to an x402 facilitator and /books' cached chain reads — the receive address's and the payer wallet's balances from a public Base RPC, the receipt of every transaction the books name from the same kind of public RPC — no indexer, no key (see src/chain.js).
• src/x402.js — the /402 range: one x402 paywall that settles for real (USDC on Base; Base Sepolia by default; v2 in the PAYMENT-REQUIRED header and v1 in the 402 body, since much deployed buyer tooling is still v1-only) and a set of paywalls that misbehave on purpose.
• src/cdp-auth.js — bearer tokens for Coinbase's CDP x402 facilitator, built with Web Crypto in the exact shape @coinbase/cdp-sdk produces (scripts/cdp-auth-test.mjs proves it against the SDK offline). Active since 2026-10-05 16:36 UTC, when the operator stored CDP_API_KEY_ID/CDP_API_KEY_SECRET as Worker secrets: CDP leads the mainnet v2 facilitator chain, and a v2 payment that CDP settles lists /402/pay/base in the CDP Bazaar (v1 payments, and payments that fail over to PayAI, do not; docs/RUNBOOK-cdp-facilitator.md). PayAI is second for the same reason: it publishes a catalogue of what it settles.
• src/sse.js — the /sse range: Server-Sent Events streams that misbehave on purpose (line endings, split UTF-8, cuts, resets, stalls, Last-Event-ID). Since v0.22.0 the index carries a witness block — what real SSE client libraries delivered at every flavor — computed from the /clients.jsonl sse rows (scripts/sse-witness/, scripts/witness-parse-sse.mjs).
• src/range.js — the /range range: resumable downloads that misbehave over a self-describing document (Range ignored, shifted or off-by-one bytes, Content-Range lies, If-Range ignored). Since v0.24.0 the index carries a witness block — what real resuming download clients left on disk when told to resume a partial file at every flavor, each row described against where RFC 9110 places the bytes a raw-wire control received — computed from the /clients.jsonl range rows (scripts/range-witness/, scripts/witness-parse-range.mjs).
• src/etag.js — the /etag range: conditional requests that misbehave (validators that change or lie, conditionals ignored, unconditional 304s, unquoted ETags, impossible dates). Since v0.25.0 the index carries a witness block — what real HTTP caches and conditional-request clients (library caches, curl --etag-compare/-z, wget -N, caching proxies) sent and handed their callers when fetching each flavor three times through a fresh cache, each row described against what RFC 9111 implies from a raw-wire control's exchanges — computed from the /clients.jsonl etag rows (scripts/etag-witness/, scripts/witness-parse-etag.mjs).
• src/cookies.js — the /cookies range: Set-Cookie edge cases (folded headers, duplicate names, supercookies, broken prefixes, unparseable dates); /cookies/echo reads back what your client sent. Since v0.20.0 the index carries a witness block — what eight real clients' jars did at every setter flavor — computed from the /clients.jsonl cookies rows (scripts/cookies-witness/, scripts/witness-parse-cookies.mjs).
• src/auth.js — the /auth range: HTTP authentication that misbehaves (challenge-less 401s, unknown schemes, multi-challenge headers, always-reject, accept-anything, the Digest stale dance, a 407 from an origin). Only the published fake credentials pass a check (/auth/accept-any checks nothing and answers authenticated:true to any non-empty Authorization header); never send real ones.
• src/compress.js — the /compress range: content codings that misbehave (gzip declared on plain text or not declared at all, streams that are truncated, corrupt, CRC-wrong, concatenated, double-gzipped or followed by junk, raw DEFLATE as deflate, the x-gzip alias, a zero-byte gzip body, a compressed body under the plaintext's Content-Length, a .gz download that is transport-encoded too, a declared decompression bomb; br, zstd and deflate; ok is the control; ?code= makes any of them an error body). Designed around what Cloudflare's edge does to each flavor for a client that did not advertise the coding — documented per flavor, dated, and pinned by the smoke suite; docs/spec-compress.md, docs/probe-compress-2026-09-01.txt (the edge matrix) and docs/probe-compress-clients-2026-09-02.txt (six real clients, scripts in scripts/compress-witness/) have the evidence.
• src/crosshost.js — the /crosshost range: what a client does with Authorization, Proxy-Authorization, Cookie and X-Api-Key when a redirect crosses a host boundary. This is the one family that needs two hostnames, so the Worker serves two: badhttp.dev and alt.badhttp.dev (same Worker, same zone, covered by the zone's existing wildcard certificate, $0). Nine flavors cross apex-to-subdomain and back, out-and-return, a port change, a protocol-relative authority, both scheme directions, and a cookie-jar scoping hop; /crosshost/land is the oracle and reports what arrived without ever echoing it. There is no open redirect: every target is a complete absolute URL in a frozen table of those two hosts, selected by flavor name and checked against a fixed pattern before it is sent — no endpoint takes a redirect target, or any part of one, from the caller. The alt host serves this family and nothing else, noindex on every response. Witnessed live against eight real clients (2026-09-10, re-captured 2026-09-17 with the jar flavor added); the 72 observations are rows of /clients.jsonl (family crosshost, harnesses in scripts/crosshost-witness/) and the /crosshost index summarizes them under witness, with every number computed from the rows.
• src/template.js — path templates requested literally (/sse/{flavor}, braces intact) answer 200 with the valid substitutions; registry probers request them constantly.
• src/page.js — the HTML catalogue (/) and books page (/books). Zero JavaScript.
• src/openapi.js — /openapi.json, in the profile agent registries parse (security: [] on every operation, x-payment-info on /402/pay).
• src/corpus.js — /corpus.jsonl (the catalogue of defects as NDJSON, one row per documented defect behaviour, generated from the same flavor tables the site renders; the template explainers and the discovery surfaces are deliberately not rows — see what_is_not_a_row on /corpus) and /license. Also carries the dated RFC 9112 finding: this service emits no message-syntax violations and cannot, because the edge re-serializes every response.
• src/books.js — the public accounts. Costs and booked revenue are hand-maintained and must match LEDGER.md line for line; hosting accrues from the clock; hosting_measured/hostingUsage() publish what this Worker actually consumes against Cloudflare's allowances (both the $0 incremental and the $5/mo standalone answer, with the free plan ruled out by a measured max CPU); solvency() answers "can it pay its own next bill?" from booked revenue alone, with the operator's capital shown separately as runway; fundingManifest() serves /funding.json.
• src/clients.js + src/witness-data.js + src/witness-crosshost-data.js + src/witness-auth-data.js + src/witness-cookies-data.js + src/witness-sse-data.js + src/witness-range-data.js + src/witness-etag-data.js — /clients.jsonl (dated observations in seven families: six real HTTP clients and two non-decoding controls against all 21 /compress flavors; eight clients started at each of the nine /crosshost flavors; the same eight clients handed the documented fake credentials through their own mechanism at each of the 18 /auth flavors; the same eight with a fresh jar at each of the 17 /cookies setter flavors; 7 real SSE client libraries plus a raw-wire control at each of the 14 /sse flavors, each row described against a reference WHATWG §9.2.6 parse of the bytes the control received — the first family whose oracle is a client-side specification, derived from the wire by scripts/witness-parse-sse.mjs; real resuming download clients, each handed a 400-byte partial and told to resume it, at each of the 14 /range flavors plus a fresh download, with every request recorded and the file on disk described against where RFC 9110 places the bytes the control received — captured by scripts/range-witness/, derived by scripts/witness-parse-range.mjs; 14 real HTTP caches and conditional-request clients, each fetching each of the 10 /etag flavors three times through a fresh cache with every request recorded and the caller's answer described against what RFC 9111 implies from the control's exchanges — captured by scripts/etag-witness/, derived by scripts/witness-parse-etag.mjs) and its /clients index. The only data here this project did not author about itself. Generated from docs/probe-compress-clients-2026-09-02.txt by scripts/witness-parse.mjs, from docs/probe-crosshost-clients-2026-09-17.jsonl by scripts/witness-parse-crosshost.mjs, and from docs/probe-auth-clients-2026-09-18.jsonl by scripts/witness-parse-auth.mjs (harnesses in scripts/auth-witness/); never parsed at runtime.
• src/books.js — hand-maintained public books; must match LEDGER.md.
• src/chain.js — /books' live reconciliation: one cached eth_call balanceOf against a public Base RPC (balance − labeled movements − booked revenue must be 0, and the page says so when it isn't) plus the receipt of every transaction the books name (eth_getTransactionReceipt, batched, from the same public RPCs — since session 30; a public Blockscout indexer served the list until it stopped answering on 2026-10-06), so each book row is confirmed against the chain or flagged on the page itself, and a transaction the books do not name shows in the balance identity rather than being implied absent. The project holds no key that can spend from the address.
• wrangler.jsonc — Worker config. npx wrangler deploy once CLOUDFLARE_API_TOKEN is set.
• scripts/smoke.sh — live checks (none of them contact a facilitator). scripts/corpus-verify.sh — replays every /corpus.jsonl row and fails if one does not address the endpoint it publishes (400/404/405/000). scripts/corpus-assert.sh — re-derives the rows' machine-readable fields from the wire: deterministic_bytes: true must survive two identical requests, false must name something in varies_by, the two RFC 9112 §6.3 violators must be exactly /truncate and /sse/drop, and each published curl must reconstruct from its own row. Both run on every deploy; if either fails, fix the row, never the check. scripts/x402-pay.mjs — pay an endpoint with the official v2 client. scripts/x402-pay-v1.mjs — the same with the legacy v1 client (x402-fetch@1.2.0: body + X-PAYMENT).
• scripts/x402scan-register.sh — (re)register the catalogue on x402scan.com from the OpenAPI document. scripts/indexnow.sh — ping IndexNow search engines after a deploy.
• scripts/state-check.sh — the session's "state found" paragraph as one command (books, balances, facilitators, catalogues, testnet receipts; --cred adds traffic and the registrar).
• scripts/find-transfers.mjs — finds USDC transfers to or from the receive address without an indexer: an eth_getLogs walk over a keyless public RPC in bounded windows (--since/--until by UTC date, --unknown for what src/books.js does not yet name). The discovery half of /books: the page confirms the transactions the books name; this finds the hash of one they do not. docs/reviews/ keeps each pre-deploy adversarial review's findings, including the ones carried to later sessions.
• docs/ — runbooks for the next session. docs/RUNBOOK-agent-teams.md — how the AI divides a session's work among subagents, and the saved workflows in .claude/workflows/ (review-frozen — adversarial review of a frozen tree; ledger-digest — one verified digest per ledger entry, rendered by scripts/ledger-digest-render.mjs).
• ledger/ — the full session entries of LEDGER.md, one file per session, moved out verbatim on 2026-10-06 (session 29) so the file every session reads stays small.

Run locally

npx wrangler dev --local
curl -i "http://localhost:8787/status/429?retry-after=3"

Endpoints

/status/{code} · /delay/{s} · /drip · /flaky/{pct} · /badjson/{flavor} · /truncate · /sse/{flavor} · /range/{flavor} · /etag/{flavor} · /cookies/{flavor} · /auth/{flavor} · /compress/{flavor} · /crosshost/{flavor} · /redirect/{n} · /redirect/loop · /headers · /echo · /402/pay · /402/{never,reject,slow,crash,bad-receipt,overpriced,wrong-network} · /402/broken/{flavor} · /corpus · /corpus.jsonl · /clients · /clients.jsonl · /license · /openapi.json · /llms.txt · /sitemap.xml · /books · /funding.json · /health

Full documentation with curl examples is the home page itself.

Licence

Two different things, and conflating them is what prompted a conformance-validator project to write in on 2026-09-06 and ask:

• What the service emits — response heads and bodies, the catalogue documents, every JSON index, /openapi.json, /corpus.jsonl — is CC0-1.0. Public domain: capture it, redistribute it, relicense it, put it in a test corpus under any licence you like. No conditions; attribution is requested, never required. Statement at /license, and on every corpus row.
• This source is MIT.

Until 2026-09-06 only the second was stated, and /openapi.json advertised it in info.license, a field that reads as the licence for the API. That field now declares CC0-1.0; the source licence lives in info.x-license.