Best real-time email validation for forms
Real-time validation stops typos and throwaway addresses at the form before they reach your list. Eight APIs ranked on what a form check returns and costs.
How this was compared
Disclosure: ZapBounce is our product. Figures were read from each vendor's own pages in September 2026, and the criteria below were applied to every entry, ours included.
The short version
- What one call returns for a form: a result, a disposable flag, a role flag and a typo suggestion you can show the person typing.
- Billing per call: whether a check that ends in unknown, a duplicate or an error spends a credit.
- Testing the form: whether you can run test submissions without spending live credits.
- Price per 1,000 checks and credit expiry, read from each vendor's own pages in September 2026.
- Disclosure: ZapBounce is our product, and the same criteria were applied to it.
At a glance
| 10,000 addresses | Credit expiry | Bills unknowns | |
|---|---|---|---|
| ZapBounce | $25 | Credits never expire | No |
| Kickbox | $70 | Credits expire one year from purchase | No |
| Emailable | $0.0076 an address at the 5,000 entry, 15% off on a subscription | Credits never expire | No |
| Bouncer | $60 | Credits never expire | No |
| QuickEmailVerification | $60 one-time | One-time credits never expire; daily subscription credits reset and do not roll over | No |
| Mailgun Email Validation | 5,000 included, then from $1.20 per 100 on Foundation | Not stated on its pricing page | Not stated |
| ZeroBounce | Subscription only | Credits roll over while the subscription is active | Not stated |
| Verifalia | $49.90 at Standard quality | Purchased credits never expire; daily free credits expire each day | Not stated |
Vendor figures read from their own pricing pages in September 2026. Confirm before purchase, because prices move.
The ranking
Best first, with the situation each one fits.
ZapBounce
Disclosure: ZapBounce is our product. Your form posts the address to POST /v1/verify and gets back valid, invalid, catch_all or unknown, with a reason, flags for role, disposable and free-provider addresses, and did_you_mean when someone types gmial.com. The suggestion is never applied for you, so the person confirms the fix.
- Best for:
- Signup, trial and lead forms that should catch a typo while the person is still on the page, at $5 per 1,000 checks with 100 free a month. See real-time verification and signup form protection.
Kickbox
Kickbox charges only for definitive results and adds its Sendex quality score to each check.
- Best for:
- Forms where a quality score decides whether to ask for a second address.
- Less suited to:
- Credits bought ahead of need, since they expire one year from purchase (read 24 September 2026).
Emailable
Emailable refunds duplicates and unknowns, its credits never expire, and new accounts get 250 free credits.
- Best for:
- High-traffic forms that will use a 5,000-credit pack quickly.
- Less suited to:
- Low-traffic forms, since purchases start at 5,000 credits.
Bouncer
Bouncer never charges for duplicates or unknowns and flags risky domains with its toxicity check.
- Best for:
- Forms that attract many risky or throwaway domains.
- Less suited to:
- Large volumes on a tight budget, where its 100,000 tier costs $400.
QuickEmailVerification
QuickEmailVerification gives 100 free credits a day with no card and does not charge for unknowns.
- Best for:
- Low-traffic forms that stay under 100 signups a day.
- Less suited to:
- Saving unused daily checks, since daily subscription credits reset and do not roll over.
Mailgun Validation
Mailgun includes 5,000 validations in its Foundation and Scale sending plans, with overage from $1.20 per 100 on Foundation (read 24 September 2026).
- Best for:
- Teams that already send their product email through Mailgun.
- Less suited to:
- Teams on another sending platform, since validation is sold inside Mailgun's sending plans.
ZeroBounce
ZeroBounce renews 100 free credits a month on a business domain and pairs its API with a deliverability suite.
- Best for:
- Teams who want verification and placement testing on one account.
- Less suited to:
- Small paid top-ups, since paid credits start at a 2,000-credit minimum for $39.
Verifalia
Verifalia reports why an address failed and gives 25 free checks a day.
- Best for:
- Forms that show the person a specific reason when an address is rejected.
- Less suited to:
- Deeper checks on a fixed budget, since its High and Extreme levels cost 2 and 4 credits an address.
Why ZapBounce ranks first
How to choose
- Typo fixing: ZapBounce returns did_you_mean on every call where a fix fits, and never applies it for you, so the person confirms the correction.
- Traffic: QuickEmailVerification gives 100 free a day and Verifalia 25 a day. ZapBounce gives 100 free a month plus sandbox tests that never spend a credit, then $5 for 1,000.
- Minimum purchase: Emailable starts at 5,000 credits and ZeroBounce at 2,000. ZapBounce has no minimum, so a quiet form pays for what it uses.
- Sending platform: Mailgun sells validation inside its sending plans. ZapBounce is called from your own form code or a Typeform or Zapier step.
Questions people ask
What is real-time email validation?
It checks an address the moment someone submits a form, through an API call, and returns a result before the signup is saved. Bad addresses are caught while the person can still correct them.
Should I validate emails on every keystroke?
No. Validate when the form is submitted, or when the person leaves the email field. Checking every keystroke fires calls on half-typed addresses and spends credits for nothing.
What should my form do with a catch-all or unknown result?
Accept the signup and tag it. Catch-all addresses often belong to real people at company domains, and unknown means the server did not answer in time. Re-check unknown rows later; ZapBounce never bills them.
Can real-time validation block disposable emails?
Yes. ZapBounce sets disposable to true when the domain is a throwaway provider, and your form can reject it with a message asking for a permanent address.
Run the same sample through two of them
100 free checks a month, no card. Compare how many addresses each one declined to judge, which matters more than either accuracy claim.