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Resend

Resend API

Yes. Resend publishes a public REST API with both auth. See resend.com/docs/introduction for pricing details.

Auth: bothOpenAPI specSDKs: node, python, go, ruby, php, javaMCP also available
Open API docsTry Resend
Public REST API documentedAgent-readiness 8/10
Data from Buddy's database, auto-rechecked weekly

What is the Resend API?

The Resend API is a public REST interface to campaigns, contacts, segments, and automation workflows. Auth is handled with either an API key (server-side) or OAuth (delegated user auth). Official SDKs cover node, python, go, ruby, php, java, which keeps boilerplate to a minimum. An OpenAPI spec is published, which means you can auto-generate typed clients from it.

Typical builds: scripts that sync subscribers from your product database, engagement dashboards that combine open rate with revenue attribution, and cron jobs that pause underperforming campaigns automatically.

For agent workflows specifically, the official MCP server is usually less code than the REST API. The API still wins for scheduled jobs, dashboards, and anything outside an LLM-driven flow.

For the broader picture: Resend review, full pricing breakdown, .

HOOK IT TO YOUR STACK

Real Resend API calls you'll write

resend-apirest
#List campaigns from the last 30 days
GET/v3/campaigns?since=30d&fields=name,open_rate,clicks
200 OK · 12 campaigns
Black Friday Teaseropen 42.1%
Product launchopen 38.5%
Weekly digest #12open 27.0%
Welcome flow step 2open 61.3%
resend-apirest
#Create a new automation programmatically
POST/v3/automations
201 Created · automation_id: aut_8x
Statusdraft
Steps configured0
Estimated audience2,847
Push steps via PUT /automations/{id}/steps.
resend-apirest
#Add a contact and tag them in one call
POST/v3/contacts
201 Created · contact_id: c_4f12
Lifecycle stagesubscriber
Tags applied1
Triggers firedwelcome-series
TMB SCORE FOR ResendAuth: bothAgent fit: 8/10
Read review →

Endpoints illustrative. Confirm exact paths against the live API docs before integrating.

How much does the Resend API actually cost?

Verify on docs

Resend publishes an API, but per-tier gating wasn't extracted automatically.

  • Most likely scenario: API access is either included in all paid plans, or it's gated to higher tiers and we need to verify on the live docs page.
  • Until verified, treat the question "which plan unlocks the API" as open. Don't budget on the assumption it's free with the cheapest paid plan.

API at a glance

Auth method
both
SDK languages
node, python, go, ruby, php, java
OpenAPI spec
yes
Webhooks
—
Structured outputs
—

Resend also has an MCP server

If you're wiring Resend into Claude / Cursor / Codex, the MCP server is usually less code than the REST API.

See Resend MCP page

What you can build with the Resend API

Three personas, three different shapes of build. Pick the row that matches how you actually ship.

SOLO DEV / FOUNDER

Glue Resend into your daily workflow

  • Pull a digest of campaign performance into your morning Slack
  • Trigger a one-off backfill when something looks off
  • Pipe data into your own SQLite for ad-hoc queries
Effort: A weekend, one Node or Python script
AGENCY / CONSULTANT

Sell Resend reporting at scale

  • White-label Resend data into client-branded dashboards
  • Run scheduled multi-account reports without logging into the Resend UI
  • Cross-reference with the rest of the client's stack (CRM, analytics, ad spend)
Effort: 1-2 weeks, hits multi-tenant auth quickly
IN-HOUSE ENGINEER

Production pipelines for Resend

  • Real-time sync into your warehouse on a cron
  • Custom alerts the dashboard's built-in alerting can't express
  • Backfill + idempotency handling for Resend data older than the dashboard exposes
Effort: Multi-week project, expect rate-limit tuning

Quickstart template

# Starter template — endpoint paths and SDK package names come from
# the Resend API docs: https://resend.com/docs/introduction

curl -X GET "https://resend.com/<your-endpoint>" \
  -H "Authorization: Bearer $TOKEN" \
  -H "Accept: application/json" | jq .

Template only. Endpoint paths, exact base URL, and auth header format come from resend.com/docs/introduction.

Limits and gotchas

  • OpenAPI is published — auto-generated clients work out of the box. Saves writing wrappers by hand.
  • Official SDKs: node, python, go, ruby, php, java. Use them to skip auth boilerplate and get type safety.
  • Rate limits: always read the docs page before scaling — the published limit is usually lower than the practical one and overages can be expensive.
8/10

Agent-readiness verdict

Strong agent-fit for Claude workflows. Resend includes an official MCP server and comprehensive API coverage with OpenAPI spec plus SDKs across 6 languages, making it straightforward to integrate into agentic email tasks. The main gap is lack of webhook support, which limits real-time event handling in multi-step workflows.

MCP server availableOfficial MCP (on tool's own domain)Public API with docsOpenAPI/Swagger spec publishedMultiple SDK languages

Resend API FAQ

Does Resend have a public API?+
Yes — REST API at resend.com/docs/introduction, auth via both.
What auth does the Resend API use?+
Both API key (server-side) and OAuth (delegated/user-auth).
Does Resend have official SDKs?+
Yes — official SDKs for node, python, go, ruby, php, java.
Is there an OpenAPI / Swagger spec I can auto-generate clients from?+
Yes — at resend.com/openapi.json.
Should I use the API or the MCP server for Claude / Cursor / Codex?+
Prefer the MCP server for agent workflows — it's less code and pre-handles auth flows. Use the REST API for scheduled jobs, dashboards, and anything outside an LLM-driven flow.

Sources

Joonas Rotko
Joonas RotkoAuthor & Founder of That Marketing Buddy

10+ years in digital marketing. I review marketing software for AI-stack fit: real pricing, MCP and API support, and how cleanly each tool drops into an AI agent workflow, cross-checked against verified data and real user feedback.

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