Spaw vs ZeroBounce
ZeroBounce is an email validation service with a pay-as-you-go credit model and a subscription (ZeroBounce ONE) that bundles deliverability tools such as activity data, inbox placement tests and blacklist monitoring.
The table uses ZeroBounce's public pricing and documentation pages as checked on 2026-09-13, and Spaw's own pricing page. A row those pages carry no value for is marked "not on the pages read" rather than guessed at, and that is a statement about the reading and not about what ZeroBounce publishes.
| spaw | zerobounce | |
|---|---|---|
| Pricing model | Pay-as-you-go credit packs whose credits never expire, or optional plans, billed monthly or yearly, that deposit the same credits every month for less and roll unused plan credits over up to three months' allowance; both through Stripe Checkout | Pay-as-you-go credits from $39 for 2,000 addresses, 15% off with autopay, or the ZeroBounce ONE subscription at $99 a month with unused credits rolling over; volume pricing shown through a calculator rather than fixed packs |
| Free tier | 100 free credits every month, no card required | 100 validation credits a month on the free account |
| Price per 1,000 at about 10k | $7.80 (Growth pack: 5,000 credits for $39), or $5.80 on the Growth monthly plan (5,000 credits for $29 a month) | not on the pages read |
| Price per 1,000 at about 100k | $4.49 (Volume pack: 100,000 credits for $449), or $3.49 on the Volume monthly plan (100,000 credits for $349 a month) | not on the pages read |
| Unknown or catch-all results billed | No: an unconfirmed mailbox (reason unverified) and an answer Spaw could not obtain because its handshake partner was unavailable are free and leave no 7-day repeat marker, so a later lookup is a fresh one; a catch-all answer costs 1 credit like any risky answer, and an automatic re-check bills 1 credit only when it confirms the mailbox | No |
| Undeliverable results billed | No, within a fair use: undeliverable answers that needed a mailbox probe are free up to max(500, your billed email answers) in a rolling 30 days, then 1 credit each; the rest are always free | not on the pages read |
| SMTP mailbox check | Yes | not on the pages read |
| Catch-all handling | A catch-all answer is remembered per domain for 7 days, and every unconfirmed mailbox carries a published 0 to 100 mailbox_confidence estimate | catch-all is one of seven statuses (valid, invalid, catch-all, unknown, spamtrap, abuse, do_not_mail) with 21 sub-statuses; only unknown results are stated to be free |
| Bulk limit | 100,000 addresses per bulk job, with an HMAC-signed completion webhook | Bulk file endpoints for larger lists; size limits not published on the pages checked |
| Batch API | 50 addresses per synchronous request, probes sent concurrently | Up to 100 emails per batch request, at most 30 requests a minute (40 on ZeroBounce ONE); the bulk file endpoints carry no rate limit |
| Rate limit | 5 requests per second per key on the email and consistency endpoints | Single validation: 80,000 requests in 10 seconds per the docs (100,000 on ZeroBounce ONE); batch: 30 requests a minute; exceeding a limit triggers a temporary block |
| Official SDKs | Python, Node.js, PHP | PHP, Python, Java, JavaScript, Node.js, C#, Go, Ruby, Rust, Kotlin, Swift |
| Data retention | Only email verification keeps a history row, for 30 days, then pruned; test addresses are never logged | not on the pages read |
checked 2026-09-13 · sources: ZeroBounce pricing, ZeroBounce API rate limits, ZeroBounce batch validation docs
When ZeroBounce fits better
Marketing teams that want a deliverability suite around verification and prefer a subscription with bundled tools.
- Credits never expire for ZeroBounce ONE subscribers and on the free account; pay-as-you-go expiry depends on the account's terms
- Unknown results never consume a credit
- ZeroBounce ONE bundles activity data, AI scoring, an email finder, inbox placement tests, blacklist and DMARC monitoring
- 24 sub-statuses explain a result, from greylisted to possible_typo and mailbox_quota_exceeded
When Spaw fits better
Developers who want one flat price per answered lookup across every signal a signup form produces, a transparent risk score, and an API that documents every field.
- Spaw lists fixed pack prices and a monthly free grant on one page; ZeroBounce prices volume through a calculator and its ONE subscription
- Both leave unknown results unbilled; Spaw also leaves undeliverable verdicts free within a fair-use allowance
- Spaw's risk score is a sum of published weights on every lookup; ZeroBounce offers AI scoring as part of its ONE subscription
- Spaw batches take 50 addresses at 5 requests a second; ZeroBounce batches take 100 addresses at 30 requests a minute
Questions
Does Spaw charge for catch-all or unknown results?
Spaw bills per answer, not per probe outcome. A catch-all domain comes back risky with reason catch_all and costs 1 credit like any risky answer. A mailbox the handshake could not confirm (greylisting, a timeout, no definite answer) comes back risky with reason unverified and is free, and so is an answer Spaw could not obtain at all because its handshake partner was unavailable; neither leaves a 7-day repeat marker, so a later lookup is a fresh one (an uncertain result is reused for up to 15 minutes, then the mailbox is asked again) and bills 1 credit only once the mailbox is confirmed, and the automatic re-checks behind callback_url bill 1 credit only when they confirm it. Undeliverable verdicts are free within a fair use of max(500, your billed email answers) in a rolling 30 days, and invalid input and repeats within 7 days are free too. ZeroBounce states that it does not bill unknown results.
Can I move a list from ZeroBounce to Spaw?
Yes. Upload the CSV to the dashboard or POST it to the bulk endpoint; Spaw keeps your columns, adds the verdict columns, and lets you download only the deliverable, risky or undeliverable rows. Addresses that come back undeliverable join your suppression list so later runs skip them for free.
Is there a free tier?
Every Spaw account receives 100 free credits at the start of each month with no card on file, and unused free credits accumulate. ZeroBounce offers: 100 validation credits a month on the free account.
Try Spaw on your own list
Free credits every month, no card. Upload a list, keep your columns, and download only the rows you want. See the pricing page for every rule, or the ZeroBounce alternatives.
ZeroBounce is a trademark of its owner. Spaw is not affiliated with it. Markdown version: /compare/zerobounce.md