API / Application Programming Interface

Integrates and debugs third-party REST and GraphQL APIs: auth, rate limits, pagination, webhooks, with reference for 147 services. Use when calling Stripe, OpenAI, GitHub, Slack, Twilio, or any external service, when a request that should work returns 401, 403, or 429, times out, hits a CORS error, or silently returns wrong data, when choosing an OAuth flow, signing requests, adding retries with backoff and idempotency keys, verifying webhook signatures, consuming SSE streams, uploading files, polling async jobs, caching with ETags, or syncing API data into a local database — with per-service gotchas and curl examples. Not for designing or building your own API.

REST and GraphQL API reference for 147 services: authentication, endpoints, rate limits, and per-service gotchas, plus pattern playbooks for everything that goes wrong between you and an API. User preferences live in ~/Clawic/data/api/ — the only location this skill writes (see setup.md on first use). If you have data at an old location (~/api/ or ~/clawic/api/), move it to ~/Clawic/data/api/.

When To Use

• User names a service to integrate ("call the Stripe API", "post to a Slack channel") → its section via API Categories below
• A request that "should work" returns 401/403/429, times out, or silently returns wrong data → debug.md and the pattern files
• Designing the client side of any integration: retries, pagination, webhooks, streaming, file transfer, async job polling
• Choosing between similar providers in a category (email, auth, media) → compare sections in the same category file
• Not for building your OWN API (routing, schema design, versioning your endpoints) — this skill documents consuming others' APIs

Quick Reference

Situation	Read
Endpoints/auth for a named service	Its category file — API Categories table below
401/403 that "should work", OAuth flow choice, JWT rejected	auth.md
Works in curl but not in code, works locally but not in prod, TLS errors, mysterious 400s	debug.md
Duplicated/missing items across pages, loop never ends	pagination.md
Timeouts, retries, flaky upstream, circuit breakers, provider outage	resilience.md
429s, rate-limit headers, quota budgeting, spending less of the limit	rate-limits.md
Polling for changes, ETag/304 conditional requests, what to cache client-side	caching.md
Mirroring API data locally, incremental sync, detecting deletions, sync token expired	sync.md
Blocked by CORS, calling an API from frontend code, key would ship to the browser	browser.md
SSE stream buffers, hangs, or cuts off; events half-parsed; WebSocket drops	streaming.md
Receiving events, signature verification, duplicate deliveries	webhooks.md
Upload rejected with 400/411/413, download corrupted or truncated, presigned URLs	files.md
202 Accepted, job polling, batch partial failures, async exports	async-jobs.md
The service speaks GraphQL (GitHub v4, Shopify, Linear)	graphql.md
Version pinning, Sunset/Deprecation headers, provider changed the API	versioning.md
Sandbox vs live, mocking providers, recorded fixtures, contract drift	testing.md
Money amounts, timestamps, big numeric IDs, unicode limits in payloads	data-formats.md
Multiple accounts/keys for one service	credentials.md
Anything else	Core Rules below, then the Official Docs link at the end of each API section

API Categories

Category	File	Services
AI/ML	apis/ai-ml.md	anthropic, openai, cohere, groq, mistral, perplexity, huggingface, replicate, stability, elevenlabs, deepgram, assemblyai, together, anyscale
Payments	apis/payments.md	stripe, paypal, square, plaid, chargebee, paddle, lemonsqueezy, recurly, wise, coinbase, binance, alpaca, polygon
Communication	apis/communication.md	twilio, sendgrid, mailgun, postmark, resend, mailchimp, slack, discord, telegram, zoom
Realtime	apis/realtime.md	sendbird, stream-chat, pusher, ably, onesignal, courier, knock, novu
CRM	apis/crm.md	salesforce, hubspot, pipedrive, attio, close, apollo, outreach, gong
Marketing	apis/marketing.md	drift, crisp, front, customer-io, braze, iterable, klaviyo
Developer	apis/developer.md	github, gitlab, bitbucket, vercel, netlify, railway, render, fly, digitalocean, heroku, cloudflare, circleci, pagerduty, launchdarkly, split, statsig
Database	apis/database.md	supabase, firebase, planetscale, neon, upstash, mongodb, fauna, xata, convex, appwrite
Auth	apis/auth-providers.md	clerk, auth0, workos, stytch
Media	apis/media.md	cloudinary, mux, bunny, imgix, uploadthing, uploadcare, transloadit, vimeo, youtube, spotify, unsplash, pexels, giphy, tenor
Social	apis/social.md	twitter, linkedin, instagram, tiktok, pinterest, reddit, twitch
Productivity	apis/productivity.md	notion, airtable, google-sheets, google-drive, google-calendar, dropbox, linear, jira, asana, trello, monday, clickup, figma, calendly, cal, loom, typeform
Business	apis/business.md	shopify, docusign, hellosign, bitly, dub
Geo	apis/geo.md	openweather, mapbox, google-maps
Support	apis/support.md	intercom, zendesk, freshdesk, helpscout
Analytics	apis/analytics.md	mixpanel, amplitude, posthog, segment, sentry, datadog, algolia

How to Navigate API Files

Each category file starts with an index table (API name → line number). Read the index, then only the section you need (50-100 lines each):

bash

head -20 apis/ai-ml.md          # index
sed -n '139,251p' apis/ai-ml.md # one API's section (OpenAI, per the index)

Core Rules

1. Raw request before client code. Reproduce with curl first; if curl succeeds and the SDK fails, the bug is in SDK config (base URL, version pin, auth header name), not the API. Chains: debug.md.

2. Backoff with full jitter, and Retry-After overrides it. sleep = random(0, min(cap, base × 2^attempt)), base 1s, cap 30-60s, max retry_max attempts (default 4; AWS "full jitter"). Attempt 3 → sleep is a random value in [0, 8s], not exactly 8s — the randomness is what prevents synchronized retry storms. If the 429/503 carries Retry-After, obey it instead.

3. Retry only what cannot double-execute. GET/PUT/DELETE are idempotent; retry freely. POST only with an idempotency key — a 500 or timeout on POST may have committed server-side (the charge went through, the response didn't). Details and key lifetime: resilience.md.

4. Status triage in this order: 401 → credential, 403 → permission, 404 → maybe permission too. 401 = the API doesn't know who you are (missing/expired/malformed token). 403 = it knows you and says no (scope, plan tier, IP allowlist). Some APIs (GitHub among them) return 404 for resources you lack access to, to avoid confirming existence — a "not found" on a resource you know exists is an auth bug, not a URL bug.

5. HTTP 200 is not success. Check the body for error/errors fields (GraphQL always returns 200 — graphql.md), batch endpoints for per-item failures (207 Multi-Status or a 200 with a mixed results array — async-jobs.md), and streams for completion (streaming.md).

6. Both timeouts, always. Set connect and read timeouts explicitly; a request without them hangs forever on a dead upstream. Values and rationale: resilience.md; for streams, read timeout means inter-chunk idle (streaming.md).

7. Credentials in headers, never in URLs. Query-param keys land in access logs, proxy caches, and browser history. Env vars only; naming scheme for multi-account setups: credentials.md.

8. Paginate to completion or say you didn't. Terminate on the API's own signal (has_more, next cursor absent) — never on item count alone. If you stop early, state that results are partial.

Status Triage

Beyond Core Rule 4's 401/403/404 chain:

Code	Meaning	First move
400	Request malformed or rejected	Read the body's error field, then debug.md Mysterious 400s
405	Method not allowed	Wrong verb — or a redirect: clients follow 301/302 on POST by re-issuing GET (trailing-slash URLs are the classic trigger)
409	State conflict	Re-fetch current state; concurrent edit or duplicate create
410	Gone permanently	Retired resource or API version (versioning.md); expired sync token (sync.md Sync Tokens)
412	Precondition failed	Your If-Match ETag is stale — re-read, re-apply, retry
415	Unsupported media type	Content-Type missing or wrong (top trap below)
422	Validation failed	Well-formed but semantically rejected — field-level errors are in the body
429	Rate limited	rate-limits.md; obey Retry-After
500	Server bug	Retry only idempotent requests (resilience.md Retry Logic)
502/503/504	Edge/LB failure or overload, often with an HTML body	Backoff and retry; check the status page (resilience.md Provider Outages)

Output Gates

Before emitting integration code or a diagnosis, check:

• Every POST/PUT/PATCH example includes Content-Type: application/json (or the API's required type)
• No secret appears in a URL, code literal, or logged output — env var references only
• Every pagination loop terminates on the API's has_more/cursor signal, not on len(items)
• Retry logic distinguishes 4xx (don't retry, fix the request) from 429/5xx (backoff and retry)
• Webhook handler verifies signature on the raw body before parsing (→ webhooks.md)
• Money handled in the currency's own convention (minor units, exponent), IDs as strings (→ data-formats.md)
• Examples reference the default_environment credential (sandbox unless the user asked for live)

Configuration

User-dependent variables. Defaults apply until the user states a preference; store them in ~/Clawic/data/api/config.yaml (loading and recording procedure: setup.md).

Variable	Type	Default	Effect
example_language	curl | python | javascript | go	curl	Language every request example is rendered in, across all category and pattern files
client_style	raw | sdk	raw	Whether examples use raw HTTP or the provider's official SDK (tradeoff: Where Experts Disagree)
default_environment	sandbox | live	sandbox	Which credential examples reference (credentials.md naming); live only on explicit request — enforced by the last Output Gate
retry_max	number (0-10)	4	Retry ceiling used in Core Rule 2's formula and all generated retry code

Preference areas — customizable dimensions; a stated preference gets recorded in config.yaml and applied:

• Tooling: HTTP client library (requests/httpx, axios/fetch, net/http) and testing tool (curl, HTTPie, Postman) — shapes every snippet
• Integrations: the user's chosen provider per category (payments → Stripe, email → Postmark) — which service section answers a generic ask
• Conventions: credential env-var naming (default scheme: credentials.md), error-handling style (exceptions vs result values) — shapes generated code
• Thresholds: org-mandated timeouts and retry budgets — override the resilience.md defaults when stated
• Safety posture: whether examples may include write/mutating calls, confirm-before-live behavior — tightens or relaxes the environment gate
• Output format: snippet-only vs annotated walkthrough — answer verbosity

Traps

Trap	Why it fails	Do instead
Missing Content-Type on POST	Many APIs parse the body as form-encoded or reject with an unhelpful 400/415	Always send Content-Type: application/json with JSON bodies
Trusting the default page size	Defaults are small; you silently process a fraction of the data	Loop until the API's completion signal (→ pagination.md)
Retrying 400 Bad Request	The request itself is invalid; identical retries burn quota and can trigger abuse detection	Fix the payload; retry only 429/5xx
Copy-pasted token fails with 401	Trailing newline or wrapping quotes from the clipboard corrupt the header	echo -n, or trim before use
Testing against production keys	Live-mode side effects (real charges, real emails) during development	Sandbox key first; gate and prefixes in testing.md and credentials.md
One giant try/catch around the whole call	401, 429, and 500 need different responses; a generic catch retries the unretryable	Branch on status class before any retry
Parsing each network chunk as one SSE event	TCP splits and merges events arbitrarily; JSON parse fails mid-token	Buffer to the blank-line delimiter (→ streaming.md)
Numeric IDs parsed as numbers	64-bit IDs overflow JS's 2^53−1 and round silently	Treat every ID as an opaque string (→ data-formats.md)
Buffering a whole download in memory	Multi-GB export = OOM that dev-sized data never showed	Stream to disk; verify against Content-Length (→ files.md)
Calling a third-party API straight from the browser	Most APIs send no CORS headers, and any key in the bundle is public	Proxy through your backend; only provider-designated browser-safe keys ship client-side (→ browser.md)

Where Experts Disagree

• Official SDK vs raw HTTP. SDKs win where auth is hard (request signing, OAuth refresh) and lose freshness — new endpoints land in the API before the SDK. Default: raw HTTP for simple bearer-token APIs; SDK when the provider signs requests or its docs treat the SDK as the primary interface. client_style records the user's side.
• Webhooks vs polling. Webhooks for volume and latency; polling is legitimately simpler when events are rare, no public endpoint can be hosted, or the poll interval is acceptable staleness. The wrong answer is webhooks without the full handler order (webhooks.md).
• Idempotency keys on every POST vs only where double-execution hurts. Every-POST buys uniform retry safety; minimalists note the bookkeeping cost. Boundary: any POST whose duplicate the user would notice (charge, email, order) gets a key — no exceptions there, optional elsewhere.

Security & Privacy

This skill is documentation: endpoint reference, auth patterns, and example requests for the external services listed above. Example endpoints belong to the respective providers (Stripe, OpenAI, etc.).

It does NOT:

• Store or manage API keys or secrets — it references env-var names; values are never read, printed, or persisted
• Make API calls on its own — the user runs the requests
• Send data to any external service

Guardrails:

• Credential discovery lists variable NAMES, never values (credentials.md Selection Rules)
• Sandbox/test credentials by default; live keys only on explicit user request
• Generated webhook handlers always verify signatures before parsing the payload

Related Skills

More Clawic skills, get them at https://clawic.com/skills/api (install if the user confirms):

• http — HTTP request patterns
• webhook — Webhook handling
• json — JSON processing

Feedback

• If useful, star it: https://clawic.com/skills/api
• Latest version: https://clawic.com/skills/api

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Part of Clawic, the verified skill library. Get this skill: https://clawic.com/skills/api.