Reference & Lookup Data · Integration
ZeroBounce
Add ZeroBounce to your product for your customers, and give your AI agents governed access to it.
ZeroBounce answers one question, whether mail to this address will land, and the shape of its answer is the thing to design around. Every check comes back as a status with a sub status behind it, and those statuses are not all yes or no: catch-all means the domain accepts everything so nothing can be proven either way, unknown means the check could not complete, and spamtrap and abuse describe addresses you can reach and should not. A product that flattens all of that into valid or invalid throws away the part that decides what to do next. There are three shapes of call to match three shapes of work: a single real time check while somebody is still typing, a batch of up to two hundred addresses in one request, and a bulk file job for an entire list where you submit, poll and collect. Checks are paid for in credits, which is precisely why the account behind a check belongs to the customer and never to you, and the balance is readable so your product can warn them before it runs dry.
In your product
Embedded for your customers. Per-tenant auth, no per-customer code, maintained by fastn.
Have each customer connect their own ZeroBounce account so the credits a check spends belong to the tenant that asked for it.
Verify an address at signup in real time, and keep the sub status rather than reducing the answer to a yes or a no.
Send a batch of up to two hundred addresses in one request for an import, and submit a bulk file job when a whole list needs cleaning.
Read the remaining credit balance so a customer hears they are running out before a check quietly stops working.
For your AI agents
Governed, audited access for the agents you build, through the MCP server.
An agent checks an address before anything is mailed to it and reports the status and sub status it got back.
An agent explains that an address came back as catch-all and that no further checking will resolve it.
An agent reports how many credits a customer has left and what their last bulk job consumed.
Example prompt
Check this list and tell me which addresses are catch-all rather than genuinely deliverable.
Set up ZeroBounce in 4 steps
- 01Enable the ZeroBounce connector in your fastn dashboard.
- 02Have each customer register their own key, so verification credits come out of their balance rather than yours.
- 03Choose where you check in real time and where you batch or submit a file, then set a cache window that stops one address being paid for twice in a week.
- 04Call it from your product and expose the same connection to your agents through the MCP gateway.
Why teams use the ZeroBounce integration
What you get by embedding it with fastn instead of building it yourself.
- Ship a ZeroBounce integration without building it. Your customers connect their own ZeroBounce account inside your product and work their lookups, results and reports there, with no per-customer code on your side.
- Handle the part that actually costs time: these are metered read sources, so an uncached lookup on every page view burns the customer's allowance. fastn owns the auth, token refresh, rate limits, pagination and breaking-change fixes, so a ZeroBounce update is not your on-call problem.
- One integration serves your product and your agents. The same governed ZeroBounce connection powers in-product features and gives AI agents scoped, audited access, so you answer questions from an authoritative outside source without holding that data yourself without wiring it twice.
Used by these teams
Compare with
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ZoomInfoWorks well with
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HubSpot
Notion
SnowflakeZeroBounce integration FAQ
How do I add a ZeroBounce integration to my product?
Enable the ZeroBounce connector in your fastn dashboard, then let each customer authenticate their own ZeroBounce account. fastn handles the OAuth flow, token storage and refresh per tenant, so there is no ZeroBounce client code in your app and no per-customer branch in your codebase. Setup is 4 steps.
Do my customers each connect their own ZeroBounce account?
Yes. Every connection is scoped to the individual customer, so each authorises their own ZeroBounce account and only ever sees their own lookups, results and reports. That per-tenant isolation is the point of an embedded integration: you support the long tail of customer setups without maintaining an integration per customer.
Can AI agents use this ZeroBounce integration?
Yes. The same connection is exposed to your agents through the fastn MCP gateway, with permissions scoped per tenant and every call audited. An agent checks an address before anything is mailed to it and reports the status and sub status it got back.
Who maintains the ZeroBounce integration?
fastn does. When ZeroBounce changes an endpoint, deprecates a field or alters its auth, the fix lands in the connector rather than in your backlog, and your customers' connections keep working.
Whose credentials does a ZeroBounce lookup run under?
Each customer's own. Quota and cost land on the customer that caused them rather than on a shared key you have to meter and re-bill, and one heavy customer cannot exhaust another's allowance.
How should ZeroBounce results be cached?
Per tenant, with a window that matches how fast the underlying data actually moves. ZeroBounce is a read source rather than a system of record, so the same query returns the same answer until the source changes, and caching is the difference between a sustainable integration and one that exhausts a customer's allowance on a busy page.
What can I build with the ZeroBounce integration?
A common starting point: have each customer connect their own ZeroBounce account so the credits a check spends belong to the tenant that asked for it. Teams also use it for the other use cases listed above, and expose it to agents for governed reads and writes.
How much does the ZeroBounce integration cost?
It is included. Pricing is based on connected accounts, not on how many connectors you enable, so adding ZeroBounce does not change your per-connector cost. You can start free with 3 connected accounts.
Add ZeroBounce to your product
Start free with 3 connected accounts. No sales call required, and no per-customer integration code.