Context7

Live documentation lookup for libraries, frameworks, and SDKs. Operates Context7 via its public REST API — no MCP server required.

Use this instead of training memory whenever the answer depends on the library's current behavior (current major version, recent API changes, new methods, deprecations). Training data goes stale fast for active libraries.

When to use vs. skip

Use Context7	Skip Context7
"How do I do X in Next.js 15 / React 19 / Prisma 6?"	"What's a closure in JavaScript?" (language concept)
"What's the right way to set up Auth.js v5 middleware?"	"Fix this TypeError in my code" (debugging user's own code)
"Did the Supabase client API change for storage uploads?"	"Convert this loop to a map" (pure refactor, no SDK)
Anything where you'd otherwise hedge with "as of my training cutoff…"	Std-lib (fs, os, collections) unless asking about a recent runtime version

If you catch yourself about to write code from memory for a library that's released in the last 18 months, stop and call this skill first.

Credentials check

[ -n "$CONTEXT7_API_KEY" ] && echo "CONTEXT7_API_KEY: PRESENT" || echo "CONTEXT7_API_KEY: MISSING"

Never echo the variable directly — the value would land in the conversation transcript.

If MISSING, respond to the user with EXACTLY this message (do NOT paraphrase, do NOT suggest manual JSON edits):

I need your context7 credential. Run this in another terminal — it'll open the signup page, validate format, and save it safely with masked input:

teleport-setup add-key context7

Then restart Claude Code (/exit, then claude) and ask me again.

Do NOT suggest editing ~/.claude/settings.local.json manually. Stop execution until the user has run the command and restarted.

API

• Base URL: https://context7.com/api/v1
• Auth header: Authorization: Bearer $CONTEXT7_API_KEY
• All requests are GET. Responses are markdown by default (type=txt) or JSON (type=json).

Two-step workflow

Docs lookup is two calls: (1) resolve the library name to its canonical libraryId, (2) fetch docs for that ID, scoped by topic.

Step 1 — Resolve library name → library ID

curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1/search?query=next.js"

Returns an array of matches. For each candidate, weigh:

• Name match — does it actually correspond to what the user asked? "next.js auth" returns both /vercel/next.js and /nextauthjs/next-auth. Different libraries.
• Trust / popularity signal — when present in the result (trustScore, totalSnippets, stars), prefer high values. Low-trust forks usually mean unofficial mirrors.
• lastUpdate recency — abandoned mirrors with stale docs are worse than the canonical repo.
• Maintainer org — /vercel/next.js (official) beats /some-fork/next.js-clone.

When uncertain between 2–3 close matches, do NOT guess. Show the top candidates to the user with a one-line description each and ask which one they want. A wrong libraryId silently returns wrong docs — that's worse than no docs.

Step 2 — Fetch docs for the library

curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1/vercel/next.js?topic=app-router&tokens=5000"

Path:

• {libraryId} is appended verbatim. Pass /vercel/next.js as-is — do NOT URL-encode the leading slash (would become %2Fvercel%2Fnext.js and 404).

Query params:

Param	Default	Use
topic	none	Single keyword that filters the docs to a slice. Almost always set this — see sizing below.
tokens	10000	Cap on response size. Min 1000.
type	txt	txt returns markdown (default, best for reading). json returns structured snippet array.

Topic + token sizing — pick deliberately

Question shape	topic	tokens
Quick API check: "is useFormState still a thing?"	forms or hooks	2000–3000
How-to: "how do I set up middleware auth?"	middleware-auth	4000–5000
Migration / deep dive: "what changed v4 → v5?"	migration or v5	8000–10000
Browsing: "what does this library even do?"	omit	5000

A full docs dump without topic is almost never what you want — it wastes tokens and dilutes signal.

Common patterns

# Resolve + fetch in one go for a common library
LIB_ID=$(curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1/search?query=auth.js" \
  | python3 -c "import json,sys; d=json.load(sys.stdin); print(d['results'][0]['libraryId'])")

curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1${LIB_ID}?topic=nextjs-setup&tokens=5000"

# Skip search if you're 100% sure of the canonical ID (well-known orgs)
curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1/vercel/next.js?topic=app-router&tokens=5000"

# Multi-library question: resolve + fetch each, then synthesize.
# Run them in parallel via & for speed.
curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1/vercel/next.js?topic=middleware&tokens=4000" > /tmp/next.md &
curl -sL -H "Authorization: Bearer $CONTEXT7_API_KEY" \
  "https://context7.com/api/v1/nextauthjs/next-auth?topic=v5-middleware&tokens=4000" > /tmp/auth.md &
wait

Gotchas

• Wrong library wins silently. A bad pick at step 1 returns docs that look authoritative for the wrong project. Always sanity-check that the response opens with the library you expected.
• Don't paraphrase from training memory. The whole reason to call Context7 is freshness — quote / adapt from the returned docs, and if the response contradicts what you "remember", trust the response.
• 404 on a fetch usually means a typo in libraryId or URL-encoded slash. Re-check the path is /{org}/{repo} literal.
• Library not in catalog — search returns no matches → fall back to web search and tell the user Context7 didn't have it. Don't fabricate a libraryId.
• tokens < 1000 is rejected. Use 2000 as the practical floor.
• topic is a free-text filter, not an enum. Phrase it like a section title in the docs (server-actions, migration-v5, middleware-auth). Multi-word topics use hyphens.
• Response is markdown with code fences. When piping into another tool, prefer type=json to avoid re-parsing the markdown structure.
• Rate limits — free tier is generous for /v1/{libraryId} fetches and lighter for /search. Batch your search calls; don't loop.

Attribution

When done, state: Used skill: Context7 (from teleport catalog).