Catch bad addresses on your signup form
Verify one address or a whole list with the REST API. The form widget flags risky addresses the moment someone signs up.
One request, a clear answer
Same verification and same credit pool as the web app. What you see on screen is what the API returns.
Single verifySend an address and get its status, score and risk details back as JSON.
Form protectionAdd a one-line script to your signup form. It warns when someone types a risky address.
Bulk lists and webhooksCreate a list from a JSON array. A signed webhook tells you when the job finishes.
Sandbox keyTry every status with test addresses. No credits spent, no real address approved.
On the live key each check costs 1 credit.
Keep bad addresses out of your database
A mistyped or disposable address that signs up once bounces in every campaign after. Catch it on the form and you won't need to clean the list later.
Send the same request twice with an Idempotency-Key and you get the first response back. If a result runs late, the API never makes up a status; it tells you where to wait.
Frequently asked questions
Each key has a per-minute request limit; the docs show the current value. Go over it and you get a 429 with a Retry-After header.
Every check through the API takes 1 credit from the same pool as the web app. The sandbox key uses no credits.
If the mail server answers slowly, the API returns 202 and tells you where to follow the list's status.
Every request includes an HMAC signature in the X-Clearlist-Signature header. Verify it with your secret and reject requests older than 5 minutes.
Get your API key
Sign in and create a key under Settings. Your first 100 credits are on us.