NeverBounce API review
The cheapest pay as you go verification, if you keep the CRM sync off
GET https://api.neverbounce.com/v4.2/single/check?key=secret_...&email=jane@acme.com # point of entry only: one-by-one list cleaning can lock the account # errors come back as HTTP 200 with a status field # results may be historical unless you switch that off
The NeverBounce API checks whether an email address will accept mail, either one address at a time at the moment somebody types it or a whole list as an asynchronous job. A credit verifies one email, and pay as you go starts at $8 for 1,000 credits, which is $0.008 each and the lowest entry rate of any verifier in this directory.
NeverBounce is owned by ZoomInfo. Its pricing page carries a ZoomInfo Technologies copyright and its status page is ZoomInfo's. Its terms of use carry a clause that matters more for this purchase than the price does. Connecting a CRM or another third-party application gives NeverBounce and its affiliates a license to extract the business contacts in it and sell them on, unless you opt out in your privacy settings.
The other thing to read before building is the usage guidelines. NeverBounce separates single verification from bulk more strictly than anyone else here, and the penalty for using the single endpoint to clean a database one address at a time is not a slowdown. NeverBounce says the account may be locked and API access disabled.
The rest of the category is in the Verification APIs listing.
What a NeverBounce verification costs at each volume
Pay as you go is sold by volume from a dropdown on the pricing page, and the price per credit falls in six steps. The table below is every option the page offers, read on 23 October 2026.
| Credits | Price | Per credit |
|---|---|---|
| 1,000 | $8 | $0.008 |
| 5,000 | $40 | $0.008 |
| 10,000 | $50 | $0.005 |
| 25,000 to 50,000 | $125 to $250 | $0.005 |
| 100,000 | $400 | $0.004 |
| 250,000 to 500,000 | $750 to $1,500 | $0.003 |
| 1,000,000 | $2,500 | $0.0025 |
| 2,000,000 | $4,000 | $0.002 |
The step that matters for most teams is the one at 10,000: $40 buys 5,000 credits and $50 buys twice as many. Credits expire 12 months after purchase, so a pack is a year's volume rather than a balance you keep. At 10,000 a month the Growth subscription at $49 is level with the pack and adds CRM auto-sync, where duplicates are not charged.
The jobs create endpoint takes a run_sample flag that estimates a list's bounce rate without spending credits. NeverBounce suggests deciding from that estimate whether to verify the whole list, and it is the cheapest way to find out that an old export is not worth cleaning.
NeverBounce API pricing, plan by plan
NeverBounce API pricing is credits, one per email, bought either as a pay as you go pack from $8 or as a Growth subscription from $49 a month.
Free
- No credit card to verify your first list
- A free list analysis with an estimated bounce rate
- NeverBounce does not state the number of test credits
Pay as you go
- $0.008 a credit, down to $0.002 at 2 million
- Credits expire 12 months after purchase
- Up to 10 lists cleaned at once
Growth
- Six volume steps, up to $999 for 1,000,000
- Unlimited parallel list cleaning
- CRM auto-sync, where duplicates are free
Enterprise
- Dedicated account manager and onboarding
- Advanced security and compliance
Growth also bundles things that are not verification: 200 AI-picked leads a month and AI scoring. If the API is all you need, the pay as you go ladder is the like-for-like comparison with other verifiers, and at every step it is below ZeroBounce's $0.0195 entry rate.
The terms say that connecting a third-party application or using an integration tool licenses NeverBounce and its affiliates to extract the business contacts in it, and to sell or sublicense them to third parties, until you opt out in the privacy settings. Data you upload for verification stays yours, so calling the API with your own lists falls outside that license, which covers only the connected integrations.
Limits on jobs, rules on behavior
NeverBounce API rate limits are published as job limits rather than a request rate. Each account can run 10 bulk jobs at once and 50 runs a day, and NeverBounce asks for no more than 10 jobs for every 100,000 items an hour. A supplied-data payload is capped at 25 megabytes, and anything larger returns a 413.
| Rule | What NeverBounce says | If you break it |
|---|---|---|
| Concurrent bulk jobs | 10 per account | Not stated |
| Runs a day | 50 per account | Not stated |
| Small jobs | No more than 10 jobs per 100,000 items an hour | Account may be locked and API access disabled |
| Single verification | Only in response to an action, such as a form submission | Account may be locked and API access disabled |
| Payload size | 25 MB on the supplied-data method | 413 Entity Too Large |
| Too many requests | No published rate | throttle_triggered, try again shortly |
How to size a job
NeverBounce publishes the shape it wants.
- Under 1 million emails, submit everything as one job, not five smaller ones.
- Over 1 million, split into 1 million chunks, one job each.
- Buffer data from a CRM locally and send it as one job.
- Use a remote URL rather than supplied data when the payload is large.
Errors that look like success
The one most likely to slip past a retry loop.
- API errors return an HTTP 200 with a status field, not a 4xx.
- Check status for success, general_failure, auth_failure, temp_unavail, throttle_triggered or bad_referrer.
- A 4xx or 5xx still means the request itself failed.
- A client that only checks the HTTP code will treat a throttle as a result.
Since version 4.1 NeverBounce runs Hybrid on every verification, which mixes the real-time check with historical data, and flags those results historical_response. Passing request_meta_data[leverage_historical_data]=0 forces the classic real-time check, which is worth doing on an address you are about to send to for the first time.
Taken together, NeverBounce limits how you use it more than how fast. The ceilings on jobs are generous for a list cleanup, and the one rule that ends integrations is using single check as a bulk tool, which is the easiest mistake to make from a script.
How to create a NeverBounce API key
A NeverBounce API key comes from a Custom Integration app: log in, create the app, and its overview page shows a key that starts with secret_. Each app has its own key, so an account can hold several, one per integration, and a key is reset from its app's page if it is compromised.
Sending the key
Three forms, all on the same key parameter.
- In the query string, as key=secret_...
- In an x-www-form-urlencoded body on a POST.
- In a JSON body on a POST.
- The 8-character username and secret from the V3 API do not work on V4.
Where it may run
NeverBounce is explicit about the browser.
- Server side only: a key in client code exposes the account.
- The Node.js SDK is server side only and needs Node 18 or later.
- For a sign-up form, use the JavaScript widget instead.
- A bad_referrer status means the source of the request is not trusted.
One key per integration is the useful default, because a throttle or a reset then touches one system rather than all of them. Prefer the POST body to the query string where you can, since a key in a URL ends up in logs.
What a NeverBounce API call looks like
The single check takes the key and the address, plus optional address_info, credits_info and a timeout in seconds, after which the result comes back unknown. A bulk job is created on one call and its results are fetched later, or pushed to a callback_url since version 4.2.
# 1. one address at the point of entry GET https://api.neverbounce.com/v4.2/single/check?key=$NB_KEY&email=jane@acme.com&timeout=10 # 2. a list as one job; credits are taken when it starts POST https://api.neverbounce.com/v4.2/jobs/create # 3. the balance and job counts GET https://api.neverbounce.com/v4.2/account/info?key=$NB_KEY
Where the NeverBounce API documentation lives
The NeverBounce API documentation lives at developers.neverbounce.com and is a readme.io site, which means every page is also served as Markdown with .md appended, and there is an llms.txt index. The NeverBounce API docs that matter are the reference getting-started page, the usage guidelines and the error handling page.
| Surface | Where | What it answers |
|---|---|---|
| Getting started | developers.neverbounce.com/docs | Custom Integration apps and where the key comes from. |
| API reference | developers.neverbounce.com/reference/getting-started | Single check, jobs, account info and the official SDKs. |
| Usage guidelines | developers.neverbounce.com/reference/usage-guidelines | The job limits and the rules that can lock an account. |
| Error handling | developers.neverbounce.com/reference/error-handling | The status codes returned inside an HTTP 200. |
| Changelog | developers.neverbounce.com/changelog/version-42 | Job callbacks, failure reasons and manual review opt-in. |
Official SDKs cover Node.js, Java, .NET and Python, and the Node.js SDK was rewritten in TypeScript for version 5. The authentication page also shows PHP, Go and Ruby clients. The legacy V3 docs are still online, so check that a snippet you copy uses a v4 path and a secret_ key.
NeverBounce on video
The section is here either way, because the absence is worth knowing: a vendor with no walkthrough of its own API is a vendor whose docs are the only way in.
We have not found a walkthrough of the API on NeverBounce's own channel yet. NeverBounce's own pricing, product and developer pages link to LinkedIn, X, Instagram and Facebook and to no YouTube channel. A channel titled "Never bounce" exists at youtube.com/@NeverBounce, but it links nothing back to neverbounce.com, so this directory cannot prove it is NeverBounce's own. When NeverBounce publishes one, or sends us one, it goes here.
A vendor video is the vendor's claim about itself, which is why it sits in its own section.
Strengths and limits
NeverBounce is the cheapest way into verification here, with rules that reward a well-built pipeline and punish a lazy one.
What it does well
- The lowest entry rate in the directory: $8 for 1,000 credits, $0.008 each.
- A published volume ladder down to $0.002 a credit at 2 million.
- A free bounce-rate estimate on a list before you spend anything.
- Job callbacks, so a bulk job does not need a polling loop.
- A switch to force real-time checks instead of historical results.
- One key per integration, each reset on its own.
Where it falls short
- Using single check to clean a list can lock the account and disable the API.
- Errors arrive as HTTP 200 with a status field.
- No published request rate for the single endpoint.
- Credits expire 12 months after purchase.
- Connected integrations contribute contacts to ZoomInfo unless you opt out.
The two columns describe a verifier priced for volume and governed by usage rules rather than rate limits. That suits a team that sends lists as jobs and checks single addresses only at the form, and suits far less well a script that loops over a CRM export calling single check.
Who should actually buy this
Buy NeverBounce when price per verification is the deciding line and you can send lists as jobs. At $0.008 a credit on the smallest pack it is less than half ZeroBounce's entry rate, and the ladder keeps falling past a million.
Use the API with your own uploads and leave the CRM integrations off, or opt out of data contribution in the privacy settings first. The verification is the same either way; what changes is whether your contacts end up in ZoomInfo's database.
Do not buy it to re-verify what a finder already verified at the moment it found the address. That is paying twice for one answer, whichever verifier you use.
Before you build against it
Four things to settle first, each one read off NeverBounce's own pages. The ticks are remembered in this browser, so you can come back to a half-finished integration.
NeverBounce 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 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.
Nothing worth quoting yet
We searched Reddit for threads about the NeverBounce API and have found none worth quoting yet. When one turns up, it goes here, and nothing on this page leans on an unquoted paraphrase.
NeverBounce API, answered
Is the NeverBounce API free?
Free test credits and a free list analysis, no credit card required. Paid use starts at $8 one-time.
How much does the NeverBounce API cost?
NeverBounce starts at $8 one-time. Its unit rate is $0.008 per credit. It bills pay as you go, by subscription or by credit pack, with a free tier. Read from NeverBounce's own pricing page on 24 October 2026.
What are the NeverBounce API rate limits?
No published request rate; bulk is capped at 10 concurrent jobs and 50 runs a day, and a throttled call returns throttle_triggered.
How do I get a NeverBounce API key?
A NeverBounce API key comes from a Custom Integration app: log in, create the app, and its overview page shows a key that starts with secret_. Requests authenticate with API key as the key parameter, in the query string or the request body. The current steps are in NeverBounce's own documentation, which is authoritative on anything that has changed since 24 October 2026.
Does NeverBounce have an MCP server?
Not one its own documentation describes, at the time of writing. NeverBounce ships a REST API, bulk or async jobs and webhooks instead.