Find work emails
Send a name and a company domain, get the address back with a confidence score. A search that finds nothing costs nothing.
Mailsumo API
Every Mailsumo tool,
from your own code
Find work emails, verify them, and pull your leads and tracking data into whatever you already use. One REST API, one key, and the same credits as the apps. Included with every paid plan.
GET /v1/finder/find
curl -G https://app.mailsumo.io/api/v1/finder/find \
-H "Authorization: Bearer ms_live_key" \
-d domain=brightwave.io \
--data-urlencode "full_name=Marie Leroy"Response
{
"search_id": "srch_8vQ2",
"result": {
"email": "[email protected]",
"full_name": "Marie Leroy",
"position": "Head of growth",
"confidence": 96,
"verification": "valid"
},
"credits_remaining": 431
} REST over HTTPS Bearer token auth OpenAPI 3.1 document Cursor pagination No extra cost
What you can build with it
Verify before you send
Check one address as a form is submitted, or 500 in a single call, and get a deliverability verdict for each, so bounces never reach your sending domain.
Sync your leads
Pull every address on your account, filtered by list, by the tool that found it, or by verification status, straight into your CRM or warehouse.
Read your tracking data
List the emails you sent from Gmail and their opens and clicks, and trigger your own workflows the moment a prospect reads one.
How it works
Included with every paid plan
No API tier, no per-seat surcharge and no sales call. Subscribe to any plan, create a key in your account and start calling.
The same credits as the apps
A lookup costs the same whether it comes from the extension or from your code, and both draw on one balance you can read over the API.
Honest, versioned URLs
Everything lives under /v1. When something has to change in a way that would break you, it will be /v2, not a surprise on a Tuesday.
Predictable responses
JSON in, JSON out, cursor pagination on every collection, and machine-readable error codes with a rate-limit budget on every response header.
Questions, answered
What does the API cost?
Nothing on top of your plan. API access comes with every paid Mailsumo plan, and calls that find or verify an address draw on the same monthly credits the extensions use. Free accounts can't create keys.
How do I authenticate?
Create a key in your Mailsumo account and send it as a bearer token. Keys never expire, you can hold several at once, and revoking one takes effect immediately.
Is there a rate limit?
120 requests a minute per account, and lower on the two endpoints that spend credits. Every response tells you what you have left and when the window resets, so you can pace a large job without guessing.
Can I generate a client?
Yes. The OpenAPI 3.1 document is public, so you can import it into Postman or point a code generator at it and get a typed client in your language.
Do you have webhooks?
Not yet. This first version is a read and request API; webhooks for opens and clicks are the next thing we want to add. Tell us what you need at [email protected] and it will shape what ships.
Build it on Mailsumo
Pick a plan, create a key in your account, and make your first call in the next five minutes. The docs have a copyable example for every endpoint.
Read the API docs