Email API

The email API built for software companies

One API for transactional and marketing email. Send your first email in minutes with a REST endpoint, typed SDKs, lifecycle workflows, and team-editable templates. Start on a free tier that doesn’t expire.

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Read the docs

Read the quickstart

Codex Claude Code

Looking for use cases? Explore the transactional email and marketing email guides.

Send your first email

Create a transactional email, copy its transactionalId, set LOOPS_API_KEY, and send it from anywhere your backend runs.

cURL

API docs

curl -X POST https://app.loops.so/api/v1/transactional \
  -H "Authorization: Bearer $LOOPS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "transactionalId": "YOUR_ID",
    "email": "[email protected]",
    "dataVariables": { "firstName": "Alex" }
  }'

Node SDK

SDK docs

import { LoopsClient } from "loops";
const loops = new LoopsClient(process.env.LOOPS_API_KEY);
await loops.sendTransactionalEmail({ transactionalId: "YOUR_ID", email: "[email protected]", dataVariables: { firstName: "Alex" } });

Python

SDK docs

from loops_so import LoopsClient

loops = LoopsClient(api_key="YOUR_API_KEY")
loops.send_transactional_email(
    transactional_id="YOUR_ID",
    email="[email protected]",
    data_variables={"firstName": "Alex"},
)

Next.js (route handler)

SDK docs

export async function POST(req) {
  const { email } = await req.json();
  await loops.sendTransactionalEmail({ transactionalId: "YOUR_ID", email });
  return Response.json({ ok: true });
}

One platform

Everything you need, behind one key

Transactional + marketing in one API

One platform, one contact record, one key.

Lifecycle workflows

Send an event, trigger multi-step automations, no cron jobs.

Editable templates

A visual editor so non-engineers can edit copy.

Webhooks

Delivery, open, click, bounce, and unsubscribe events.

Deliverability built in

SPF, DKIM, DMARC, and managed IP reputation.

Audiences & contacts

One contact API with custom properties and lists.

Free tier

A free tier that doesn’t expire

1,000 contacts and 4,000 email sends per month, all features included. Transactional email is included on the free plan and counts toward your 4,000 monthly sends. It’s not unlimited.

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Buyer guide

How to choose an email API for SaaS

A good SaaS email API should handle transactional, marketing, and lifecycle email without forcing your team to stitch together separate systems. Use these criteria when comparing providers: developer experience, deliverability, template workflow, event data, observability, and pricing.

Developer experience

Look for a simple REST endpoint, typed SDKs, clear docs, local setup paths, and server-side API-key handling that works in your existing stack.

Deliverability

Authentication, sending-domain setup, bounce handling, spam complaint suppression, and inbox-placement guidance should be built into the workflow.

Template workflow

Product and marketing teams should be able to edit reusable templates while developers pass variables, fallbacks, and transactional IDs from code.

Data model

The API should share contacts, events, and properties across transactional sends, campaigns, and lifecycle workflows instead of fragmenting customer state.

Observability

You need visibility into send status, bounces, complaints, and failures so transactional email is debuggable like the rest of your product.

Pricing

Compare the free tier, contact limits, monthly send volume, transactional-email costs, and how pricing changes as your SaaS product scales.

Where Loops fits

Loops is a fit when you want one product for API-triggered transactional email, no-code marketing email, lifecycle workflows, team-editable templates, and shared contact data. If you only need raw SMTP relay with no product or marketing workflow, a lower-level infrastructure provider may be enough.

Compare plans on pricing

Transactional vs marketing vs lifecycle requirements

Split the jobs before choosing an email API. Transactional email covers one-to-one product messages like verification, password resets, receipts, and billing notices. Marketing email covers audience sends such as newsletters, product announcements, and promotions. Lifecycle email covers event-triggered journeys such as onboarding, activation, trial conversion, and win-back. Early teams can optimize for transactional reliability first, but SaaS teams with growth loops should evaluate the whole lifecycle system.

Implementation checklist

Before picking a provider, confirm server-side bearer-token authentication, official SDKs for your backend language, clear rate-limit guidance, transactional templates with request-time data variables, product events for workflows, unsubscribe handling for audience sends, webhooks for delivery and failure states, suppression handling, sending-domain setup, and pricing that will still make sense as lifecycle volume grows.

When another provider type is a better fit

A transactional-only API can be enough if you only send system messages and have no marketing or lifecycle plans. A newsletter tool can be enough if your product does not need server-triggered transactional messages or event-driven journeys. An enterprise suite can be better when procurement, multi-brand governance, or custom reporting matters more than speed. Self-managed SMTP only makes sense when a team is ready to own reputation, monitoring, bounces, complaints, templates, and compliance mechanics.

Email API buyer guide FAQ

What is the best email API for developers?
The best email API is the one that matches your product’s email model: reliable transactional sending, strong SDKs and docs, editable templates, event-triggered lifecycle workflows, webhooks, deliverability support, and a shared contact model for marketing and transactional email.

Should I use one provider for transactional and marketing email?
Use one provider when your product needs a shared customer record, unified unsubscribe state, lifecycle workflows, and editable templates across transactional and marketing email. Use separate providers only when the teams, data, compliance requirements, or infrastructure constraints are intentionally separate.

Where does Loops fit among email APIs?
Loops fits teams that want a developer-friendly email API plus lifecycle and marketing email in the same product. It is useful when engineers need server-side sending and product teams need workflows, campaigns, templates, personalization, and contact state without a second tool.