--- title: Top APIs & Integrations Skills for Codex slug: top-apis-integrations-skills-for-codex type: category-agent-cut category: apis-integrations agent: codex canonical: https://top-agent-skills.com/top-apis-integrations-skills-for-codex verified: 6 unverified: 16 updated: 2026-06-22 --- # Top APIs & Integrations Skills for Codex For API integration work in Codex CLI, the verified set is vendor-first: Paddle for merchant-of-record billing, Twilio for messaging, Resend for transactional email, and WorkOS for enterprise auth flows. Anthropic's system-design skill is the one to add when the question is how the integration should be shaped rather than which SDK call to make. ## Verified on Codex CLI (6) ### 1. resend — score 59/100 (verified-org) Resend's own API skill: send transactional and batch email, handle inbound webhooks, and manage domains, templates, and keys. - Best for: Wiring Resend into an app — transactional sends, batch sends, inbound webhook handling, and domain/template/key management. - Not ideal for: Non-Resend providers (SendGrid, Postmark, SES) — the SDK calls and webhook signatures are Resend-specific. - Publisher: Resend · MIT - Verified on: claude-code, cursor, codex ```bash npx skills add resend/resend-skills ``` Full entry: https://top-agent-skills.com/skill/resend-email (https://top-agent-skills.com/skill/resend-email.md) ### 2. workos — score 54/100 (official-anthropic) Full-stack WorkOS implementation with auth provider migration paths. - Best for: Adding WorkOS auth to a new app, or migrating from Auth0/Clerk/Cognito/Firebase/Supabase/Stytch/Descope/Better Auth. - Publisher: Anthropic · MIT - Verified on: claude-code, cursor, codex, antigravity Install: Built into Claude Code. Invoke with /workos. Full entry: https://top-agent-skills.com/skill/workos (https://top-agent-skills.com/skill/workos.md) ### 3. workos-widgets — score 54/100 (official-anthropic) Drop-in WorkOS widgets with backend token wiring across every major framework. - Best for: Embedding WorkOS user-management UI in an existing app without rebuilding auth screens. - Publisher: Anthropic · MIT - Verified on: claude-code, cursor, codex, antigravity Install: Built into Claude Code. Invoke with /workos-widgets. Full entry: https://top-agent-skills.com/skill/workos-widgets (https://top-agent-skills.com/skill/workos-widgets.md) ### 4. paddle-agent-skills — score 53/100 (verified-org) Paddle's own integration playbook: ten skills for Checkout, webhooks, pricing pages, and subscription lifecycle on the merchant-of-record platform. - Best for: Building or reviewing a Paddle Billing integration — catalog, Checkout, webhooks, customer portal, and subscription upgrade/downgrade/cancel — where Paddle handles payments, tax, and compliance as merchant of record. - Not ideal for: Paddle Classic (these skills target Paddle Billing only) and non-Paddle processors such as Stripe or Lemon Squeezy. - Publisher: Paddle · Apache-2.0 - Verified on: claude-code, codex, cursor, gemini-cli ```bash /plugin marketplace add PaddleHQ/paddle-agent-skills ``` Full entry: https://top-agent-skills.com/skill/paddle-agent-skills (https://top-agent-skills.com/skill/paddle-agent-skills.md) ### 5. twilio — score 53/100 (verified-org) Twilio's official Developer Kit: 55 skills across SMS, WhatsApp, Voice, Verify, SendGrid, and compliance — plus the Twilio MCP. Public beta. - Best for: Wiring Twilio messaging or voice into an app — SMS/WhatsApp sends, verification flows, and the A2P 10DLC compliance setup most teams skip until it blocks them. - Not ideal for: Production-critical work that needs a support SLA — the kit is Public Beta, not covered by Twilio Support Terms or SLA, and some features are unimplemented. For transactional email alone, the focused Resend skill is lighter. - Publisher: Twilio · MIT - Verified on: claude-code, cursor, codex ```bash /plugin marketplace add twilio/ai ``` Full entry: https://top-agent-skills.com/skill/twilio-skills (https://top-agent-skills.com/skill/twilio-skills.md) ### 6. system-design — score 51/100 (official-anthropic) System design from requirements. APIs, data, boundaries, scale. Full entry: https://top-agent-skills.com/skill/system-design (https://top-agent-skills.com/skill/system-design.md) ## In APIs & Integrations but NOT verified on Codex CLI (16) These may well work — the SKILL.md format is shared. They are listed as unverified because this site lists an agent only where the install was run or the publisher documents a path for it. - stripe-best-practices — Stripe's own integration playbook: pick the right API, set up Connect and billing, and handle keys and webhooks securely. (https://top-agent-skills.com/skill/stripe-best-practices) - stripe-projects — Provision a Postgres, Redis, auth, or LLM provider through the Stripe Projects catalog rather than signing up by hand. (https://top-agent-skills.com/skill/stripe-projects) - stripe-directory — Find vendors and partners for a job-to-be-done — and, where supported, let the agent purchase and consume the service. (https://top-agent-skills.com/skill/stripe-directory) - webhook-skills — Hookdeck's webhook playbook: 40 provider-specific skills covering signature verification, idempotency, and event handling — each with runnable examples. (https://top-agent-skills.com/skill/hookdeck-webhook-skills) - composio — Composio's official skill for connecting agents to 1000+ external apps: auth configs, per-user connections, tool execution, and triggers. (https://top-agent-skills.com/skill/composio-tool-router) - block-kit — Slack's own Block Kit skill — and the rare vendor skill that needs no token, because it validates against Slack's public API. (https://top-agent-skills.com/skill/slack-block-kit) - connect-recommend — The marketplace architecture decision, made with a compatibility matrix that blocks invalid Connect configurations instead of describing them. (https://top-agent-skills.com/skill/stripe-connect-recommend) - hubspot-agent-skills — First-party HubSpot CRM operations for agents: lookups, deals, quote-to-cash, reporting. (https://top-agent-skills.com/skill/hubspot-agent-skills) - hubspot-admin-skills — A HubSpot admin in a plugin: audits, dedup, scoring, lifecycle hygiene — 37 skills deep. (https://top-agent-skills.com/skill/hubspot-admin-skills) - fhir-developer-skill — The standalone FHIR skill: modeling, validation, SMART on FHIR — without the full healthcare plugin. (https://top-agent-skills.com/skill/fhir-developer-skill) - box — Box as an agent surface, plus the contract-review workflows nothing else in the catalog covers. (https://top-agent-skills.com/skill/box-for-ai) - zotero-skills — Programmatic access to the reference manager academia actually uses. (https://top-agent-skills.com/skill/zotero-skills) - norman-finance — The ledger, not the checkout: categorise, reconcile, invoice, file. (https://top-agent-skills.com/skill/norman-finance) - carta-cap-table — The equity stack: cap table, 409A history, conversions, exit waterfall. (https://top-agent-skills.com/skill/carta-cap-table) - vibe-prospecting — The top of the funnel: find the company, find the person, enrich the row. (https://top-agent-skills.com/skill/vibe-prospecting) - gtm-eng-skills — Waterfall enrichment as a procedure, not a single provider call. (https://top-agent-skills.com/skill/gtm-eng-skills) ## Common question **Why is this list shorter than the same category for Cursor?** Because it lists only what was verified on Codex, not everything that plausibly works. Several vendor skills in this category have been tested on Claude Code and Cursor but not yet on Codex — they are absent here by policy rather than because they failed. The category page shows the full set with per-agent badges. --- _Top Agent Skills. Machine-readable twin of https://top-agent-skills.com/top-apis-integrations-skills-for-codex._