ZeroBounce API review
Real-time validation with published limits and 100 free checks a month
GET https://api.zerobounce.net/v2/validate?api_key=...&email=jane@acme.com # 80,000 validations per 10 seconds, then a 1-minute block # "unknown" costs 0 credits, but 20+ unknowns in a batch # response more than once an hour blocks you for an hour
The ZeroBounce API is the verification gate in this directory: you hand it an address and it tells you whether mail to that address will land. It and NeverBounce are the two providers here built for that one job, and both can be used properly without a subscription. Here $39 buys 2,000 validations as a one-time purchase, which is $0.0195 each.
The ZeroBounce email validation API covers more than a yes or no. A validation returns a status and a sub-status, such as greylisted, role-based or a possible spam trap, and the same credit balance pays for AI scoring and an email finder. Unknown results and duplicates cost nothing.
What makes it worth reading closely is how it enforces its limits. Most APIs slow you down when you go too fast. ZeroBounce blocks you, for anything from a minute to a day depending on the endpoint, and it has a second rule about unknown results that a list cleanup can trip without exceeding any rate at all.
The rest of the category is in the Verification APIs listing.
One credit balance, several endpoints
Everything here draws on one pool of credits, and the ZeroBounce API spells out what each call takes from it. The useful split is between validating an address you already have and finding one you do not.
| Endpoint | What it does | Credits |
|---|---|---|
| /v2/validate | One address in real time, with status and sub-status. | 1, or 0 for an unknown |
| /v2/validatebatch | Up to 100 addresses in one request, results in up to 70 seconds. | 1 per address |
| Bulk file endpoints | Upload a file of any size, with anti-greylisting, and collect the results later. | 1 per address |
| AI scoring | A quality score for an address, on top of or instead of validation. | 1 per address |
| Email Finder | An address from a name and a domain. | 20 per successful query, 0 for unknown |
| /v2/getcredits | Your remaining balance. | Free |
Validating and scoring the same address costs two credits, so decide which one you need before wiring both. The finder is the expensive line: at 20 credits a query it is $0.39 at the pay as you go rate, which is the reason ZeroBounce is a verifier first and a finder only when you have nothing else.
ZeroBounce publishes a set of sandbox addresses that return each status without using credits. Wire your parsing and your retry logic against those first, and keep the 100 free monthly credits for a real sample of your own list.
ZeroBounce API pricing, plan by plan
ZeroBounce API pricing comes in two shapes: one-time credit packs that start at $39, and a monthly subscription called ZeroBounce ONE from $99.
Free
- For accounts on a business or premium email domain
- Renews monthly
- Full API access
- Enough to measure your own list quality
Pay as you go
- The minimum purchase, at $0.0195 each
- Add credits as you need them
- No charge for unknown results or duplicates
ZeroBounce ONE
- You pick the monthly credit volume, minimum 10,000
- Unused credits roll over each month
- Higher API rate limits and Activity Data
Enterprise
- Contact sales for the price
- Email Finder still costs 20 credits per successful query
ZeroBounce says the subscription saves up to 18% a month against pay as you go, depending on volume. The subscription page sets the credit volume with a number box rather than a published ladder, so this page does not model a cost per credit on it. Price your own volume on their page before assuming the subscription is the cheaper route.
Credits never expire while a ZeroBounce ONE subscription is active. Without one, ZeroBounce says expiration rules may apply depending on when the credits were bought or granted, and points to its terms rather than stating a period. If you buy a large pack and use it slowly, read those terms first.
They block rather than throttle
ZeroBounce API rate limits are published per endpoint, and the response to going over is a temporary block rather than a slowdown. The validate endpoint allows 80,000 requests in 10 seconds, 100,000 on ZeroBounce ONE, and exceeding it blocks you for a minute. The batch endpoint allows 30 requests a minute of up to 100 addresses each, 40 on ZeroBounce ONE, with a ten-minute block.
| Endpoint | Limit | If you exceed it |
|---|---|---|
| /v2/validate | 80,000 per 10 seconds (100,000 on ONE) | Blocked for 1 minute |
| /v2/validatebatch | 30 requests a minute of 100 addresses (40 on ONE) | Blocked for 10 minutes |
| /v2/getcredits | 80,000 an hour (100,000 on ONE) | Blocked for 1 day |
| /v2/getapiusage | 800 an hour (1,000 on ONE) | Blocked for 1 hour |
| Activity Data | 80,000 an hour (100,000 on ONE) | Blocked for 1 hour |
| Bad API key | 200 in an hour | Blocked for 1 hour, or 1 day on getcredits |
The unknown-result rule
This is the one most likely to stop a cleanup job.
- An unknown result costs no credits, which makes it feel free.
- A batch response with more than 20 unknown statuses, that are neither greylisted nor antispam, more than once an hour blocks you for an hour.
- A stale list from an old domain can produce exactly that pattern.
- Send suspect lists through the bulk file endpoints, which ZeroBounce recommends for large uploads without the real-time rate limits.
The other ways to get blocked
Two general rules apply to every endpoint.
- 100 bad requests in a minute, such as a missing email parameter, blocks you for an hour.
- 100 requests to an endpoint that does not exist in two minutes does the same.
- A 403 can also come from API Shield, a protection ZeroBounce switches on and off with traffic.
- A 429 means you have hit a rate limit and should back off.
The credit balance endpoint is free to call, so it is tempting to check it before every validation. Its limit is 80,000 an hour and the block for exceeding it is a full day. Read the balance once per job, not once per address.
Put together, the ceilings are high enough that a well-built pipeline never sees them, and the penalties are long enough that a badly built one finds out the hard way. Validate the shape of your requests in the sandbox, cache the balance, and route old or doubtful lists to the bulk file endpoints rather than the real-time ones.
How to create a ZeroBounce API key
A ZeroBounce API key is created on the API Keys page of your account, and a free account gets one immediately. Every request carries the key as an api_key parameter, in the query string for a GET or in the form body for a POST, which the validate endpoint has accepted since September 3, 2026.
Several keys, one master
Worth setting up properly on day one.
- Every account has a Master Key that cannot be deleted.
- Create additional keys with a name and an active state.
- Each key can be restricted to an IP address or an IP range.
- Regenerating a key replaces it, so rotate in a quiet window.
Where the request goes
Three hosts, and the choice is about data residency.
- api-us.zerobounce.net processes only in the United States, and ZeroBounce says so explicitly.
- api-eu.zerobounce.net processes only in the European Union.
- api.zerobounce.net is the previous host, now used for EU processing.
- ZeroBounce says it deletes uploaded data after 30 days.
ZeroBounce's documentation says the API may not be used externally within a third-party product, platform or service under its standard terms. That use needs prior approval and a separate commercial agreement with a minimum commitment. If the validation runs inside software you sell, settle that before you build.
A key in a query string ends up in access logs and proxy caches, so prefer the POST form where you can and restrict each key to the IP addresses it should come from. And decide early whether your use is internal, because the external-use rule changes what you are buying rather than how you call it.
What a ZeroBounce API call looks like
The validate call needs two parameters, your key and the address, and takes an optional timeout of 3 to 60 seconds, 30 by default. When the timeout is reached the answer comes back unknown rather than as an error, and an unknown costs nothing.
# 1. one address, real time GET https://api.zerobounce.net/v2/validate?api_key=$ZB_KEY&email=jane@acme.com&timeout=10 # 2. up to 100 addresses in one request POST https://api.zerobounce.net/v2/validatebatch # 3. the balance, once per job GET https://api.zerobounce.net/v2/getcredits?api_key=$ZB_KEY
Where the ZeroBounce API documentation lives
The ZeroBounce API documentation is organized by product, and the pages that matter for an integration are the quickstart and the API dashboard section, which holds the rate limits and error codes. ZeroBounce also publishes wrappers for 15 languages and platforms and a Postman collection.
| Surface | Where | What it answers |
|---|---|---|
| API quickstart | zerobounce.net/docs/email-validation-api-quickstart | Every validation endpoint, its parameters and its response. |
| API dashboard | zerobounce.net/docs/api-dashboard | Rate limits, error codes, TLS and key management. |
| API wrappers | zerobounce.net/docs/zerobounce-api-wrappers | SDKs for PHP, Python, Java, Go, Node, C#, Rust and more. |
| MCP server | zerobounce.net/docs/api-integrations/zerobounce-mcp-server/setup | The open-source server, installed from npm and run with your API key. |
| Status | status.zerobounce.net | Whether a slow response is you or them. |
| Pricing | zerobounce.net/pricing | Credit packs, ZeroBounce ONE and what each tool costs. |
The batch endpoint is the one without an SDK, which ZeroBounce says plainly on its page. Everything else has a wrapper, so for most stacks the integration is a package install and a key rather than a hand-written HTTP client.
The MCP page lists ZeroBounce's MCP access alongside the others in this directory.
ZeroBounce's own walkthrough of the API
ZeroBounce publishes this on its own channel, so it is ZeroBounce's account of ZeroBounce, not ours. It is here because a rate card cannot show you the thing moving, and a few minutes of the product is faster than any paragraph on this page at telling you whether the shape of it fits yours.
YouTube · ZeroBounce How to Get Started with ZeroBounce's Email Validation API 8:09 · Published February 2023Eight minutes from February 2023, chaptered by surface: the API dashboard, the real-time single validator, batch and bulk validation, Activity Data, bulk scoring, the SDKs, the Postman collection, the status page and checking usage. It is the best single map of what the ZeroBounce API covers. It is also more than three years old, so every price and credit cost on this page is read off the pricing page rather than off the video.
Published 27 February 2023 on ZeroBounce, the channel ZeroBounce's own pages link to, and read on 23 October 2026. Nothing in it is a source for a price or a limit on this page: every figure in the tables above comes from a ZeroBounce page.
Strengths and limits
ZeroBounce does one job, prices it honestly, and punishes careless integrations harder than anyone else here.
What it does well
- Usable without a subscription: $39 buys 2,000 validations and the credits are yours.
- Unknown results and duplicates cost nothing, so you pay for answers rather than attempts.
- A real free tier of 100 validations a month with full API access, on a business email domain.
- Rate limits published per endpoint, with the penalty for each.
- Regional hosts, including one that processes only in the United States.
- SDKs for 15 languages and platforms, and sandbox addresses for testing.
- An official open-source MCP server, installed from npm and run with your API key.
Where it falls short
- Going over a limit blocks you for a minute to a day rather than slowing you down.
- More than 20 unknowns in a batch response, more than once an hour, blocks you even under every rate limit.
- Using it inside a product you sell needs separate approval and a minimum commitment.
- The Email Finder costs 20 credits a query, which makes it a poor finder.
- Credits can expire without a subscription, under terms the pricing page does not spell out.
The pattern in those two columns is a provider that is generous on price and strict on behavior. That suits a pipeline that validates before it sends and is built once, carefully, against the sandbox. It suits an integration that retries blindly or pushes an old list through the real-time endpoint far less well.
Who should actually buy this
Buy ZeroBounce when you have addresses from somewhere that does not verify them, and you need to know which ones will land before a sending tool charges you for the attempt. That is its whole job, and NeverBounce is the only other provider here that does it without a subscription.
Do not buy it to verify what Findymail, Prospeo or FullEnrich already verified at the moment they found it. That is paying twice for one answer, which is the complaint practitioners raise most often about this category.
Read the limits page before you write code. The thresholds are generous and the blocks are long, and the unknown-result rule is the one that catches teams cleaning an old list through the real-time endpoint. Send those lists through the bulk file endpoints instead.
ZeroBounce is one of the providers in the waterfall email enrichment and inbound speed to lead stacks on this site, where the cost is worked out end to end.
Before you build against it
Five things to settle first, each one read off ZeroBounce's own pages. The ticks are remembered in this browser, so you can come back to a half-finished integration.
If ZeroBounce is not the answer
Four providers in the Verification APIs listing that solve the same problem differently. Each one is a trade, and the trade is named.
NeverBounce
$8 one-timeThe other standalone verifier here, at $0.008 a credit on the smallest pack and $0.002 at two million.
Findymail
$99/moVerification included in the find, so there is no separate step and no second bill. The right answer if you are buying both anyway.
FullEnrich
$29/moEvery email and phone verified before it is charged, and landlines cost nothing.
LeadMagic
$99/mo0.25 credits a validation on the same balance as your enrichment, if you are already a customer.
The full set, organized by the reason people leave, is on the ZeroBounce alternatives page.
ZeroBounce against the obvious rival
Same rate cards, read side by side, with the arithmetic done on a worked volume rather than left to you: ZeroBounce vs LeadMagic and ZeroBounce vs NeverBounce. Every pairing in the directory is on the compare hub.
Calling these APIs one by one? Run them from one Clay table.
Clay runs a waterfall across 150+ data providers from one table, without a separate contract with each. A lookup that finds nothing costs no data credit, and the free plan includes 500 actions a month.
Frontal is a Clay Elite Studio Partner.
What ZeroBounce users say, in their own words
The one part of this page that is not a vendor claim. Quotes are transcribed as written and linked to the thread.
Buying verification twice is the mistake, not buying it at all
switched f4om zerobounce to just using prospeo's verification maybe 4 months ago. way more reliable on B2B emails, like our bounces went from around 4% down to under 1% which was huge for us. plus you get the contact data and verification in one place so your not paying twice for basically teh same thing. only gripe is the UI could be a bit more polished but the data quality makes up for it
r/EntrepreneurRideAlong · April 2026 · 6 points
This is the routing argument from the waterfall stack on this site, arrived at from the other direction. A provider that verifies at the moment it finds has already done the work, so pushing its output through a separate verifier is a second invoice for one result. Prospeo and Findymail both verify at find time and FullEnrich bundles it, which is why the modeled stack sends only Apollo's output here.
The bounce rates are one team's own sending on their own list rather than a benchmark, and no provider in this category publishes a match rate you can hold it to. Take the structure of the complaint and measure the percentages yourself.
A verified address is verified on the day you checked it
the problem with b2b verification is that companies change their email systems way more often than people realize, especially smaller ones. what looks "verified" today might bounce tomorrow because they switched providers or updated their mx records. for what it's worth, newer companies are definitely trickier - their domains don't have the email history that verification services rely in. [...] the double-paying thing is real pain too.
r/EntrepreneurRideAlong · April 2026 · 2 points
The mechanism is the useful half. A verification is a statement about an MX record and a mailbox on the day the check ran, and a company that moves mail provider invalidates it without telling anybody. That is the argument for verifying close to send rather than verifying a list once and sending from it all quarter.
The part about newer domains is this commenter's own experience and not something measured here. Several people in the same thread report recently registered domains being flagged as risky, which is a provider protecting its own accuracy statistics at the cost of your list, so test it on your own rows before treating catch-all handling as a reason to switch.
At steady volume somebody always does the arithmetic on building it
i value my time a lot, which is why i automated it. [...] it runs in the background. upload csv, walk away, clean list comes back. zero hands-on time per run. took about 20 hours to build. at my current volume the verification services would cost a few thousand a year. now it costs nothing. the expensive option was keeping the subscription.
r/n8n · February 2026 · 3 points
Verification is the line in a waterfall where the rate is low and the volume is the entire list, which is what makes it the line that invites a build. The arithmetic is real at a few thousand a year: twenty hours of engineering pays back inside a quarter.
What it leaves out is what the paid services are actually selling, which is IP reputation and the deliverability of the check rather than the SMTP handshake itself. Another commenter in the same harvest makes that point about open-source verifiers hitting trouble at scale. Build it if your volume justifies it, and compare your bounce rate against what you were getting before rather than against the saving.
14 threads read on 13 October 2026, searched by vendor name. Scores and dates are the comment's own. Nothing here is the only source for a price or a limit on this site: every figure in the tables above comes from a vendor's own page.
ZeroBounce API, answered
Is the ZeroBounce API free?
Free plan, 100 validation credits per month for accounts on a business or premium email domain. Paid use starts at $39 one-time.
How much does the ZeroBounce API cost?
ZeroBounce starts at $39 one-time. Its unit rate is $0.0195 per validation. It bills pay as you go, by subscription or by credit pack, with a free tier. Read from ZeroBounce's own pricing page on 24 October 2026.
What are the ZeroBounce API rate limits?
80,000 validations per 10 seconds, then a one-minute block; batch at 30 requests a minute of 100 emails.
How do I get a ZeroBounce API key?
A ZeroBounce API key is created on the API Keys page of your account, and a free account gets one immediately. Requests authenticate with API key as the api_key parameter, in the query string or, since September 3, 2026, a form-encoded POST body. The current steps are in ZeroBounce's own documentation, which is authoritative on anything that has changed since 24 October 2026.
Does ZeroBounce have an MCP server?
Yes. Official open-source server, installed with npm (@zerobounce/mcp) and run with your API key; tools for validation, bulk, AI scoring, email finder and domain search. It is listed with the others on the MCP page.