# KaijuVerifier, free, POST /api/v1/verify-single, Verify a single email (authenticated): Email verification API

> Block fake signups, burner accounts, and hard bounces at the edge in 3 lines of code.

KaijuVerifier's email verification API on its Free plan. It costs $0.00 per 1,000 emails. It returns 3 of the 6 key fields we check: Address, Deliverability, Confidence.
We rank 2,467 plans by price. [treg's top-up from $10](https://datacircle.dev/validate-email-apis/treg/top-up-from-10/llms.txt) costs the least per 1,000 emails: $0.00 on average. treg asks one provider after another until one answers. You pay $26.95 per 1,000 emails when no provider answers.
[Enrich.so](https://datacircle.dev/validate-email-apis/enrich-so/149-monthly/llms.txt), [GetProspect](https://datacircle.dev/validate-email-apis/getprospect/369-pack/llms.txt) and [treg](https://datacircle.dev/validate-email-apis/treg/top-up-from-10/llms.txt) are the best email verification API providers in our benchmark.

- This page: https://datacircle.dev/validate-email-apis/kaijuverifier/free-post-api-v1-verify-single-verify-a-single-email-authenticated
- [Best email verification API in 2026](https://datacircle.dev/best-email-verification-api.txt)
- Get it: https://kaijuverifier.com/pricing
- Request: `POST https://kaijuverifier.com/api/v1/verify-single`, Verify a single email (authenticated)
- API key: with the plan, on https://kaijuverifier.com/pricing
- Its API docs: https://kaijuverifier.com/api-docs
- Sold by: KaijuVerifier (https://kaijuverifier.com)
- Checked: 2026-10-20

## In the answer

- Completeness: 50%
- Address: ✓
- Deliverability: ✓
- Confidence: ✓

## Price

- $ per 1,000 emails: $0.00
- Per: call
- Billing: free

## Aggregators

- Aggregators: none

## Charges

- Also pays for: from the same budget: Verify a batch synchronously · Submit an async bulk job · Verify a single email with the SMTP probe (authenticated) · Verify a batch synchronously with the SMTP probe · Submit an async bulk job with the SMTP probe

## Not found

- $ per 1,000: $0.00

## Catch-all

- $ per 1,000: $0.00

## Bounce

- Bounce refund: the verification credits in full, when the campaign's hard-bounce rate exceeds 2% on addresses verified as Valid

## In their words

- Their pitch: Block fake signups, burner accounts, and hard bounces at the edge in 3 lines of code.

## Data

- Freshness: stored (DNS valid, MX count, MX providers, MX grade: live)
- Keep data: no limit
- Use data: You agree NOT to use the Service for: Sending SPAM or unsolicited bulk emails, Verifying email lists obtained illegally or without consent, Any activity that violates GDPR, CAN-SPAM, or other data protection laws, Attempting to reverse engineer, hack, or abuse the Service, Reselling or redistributing verification results without authorization

## Plan

- Pay: $0
- You get: 100 credits a month
- Enough for: 100 calls a month

## Rate limit

- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: email. Optional: use_smtp
- Method: POST
- Path: /api/v1/verify-single

## About the plan

- Plan: Free
- Who can get it: anyone

## The 22 fields the plan's answer can hold

success, email, normalized email, safe to send, status, reason, confidence, score, grade, did you mean, syntax valid, DNS valid, catch-all, disposable, role address, free provider, MX count, MX providers, MX grade, quota limit, quota used this month, quota remaining

## KaijuVerifier's plans (12)

- [KaijuVerifier, free, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/free-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $0.00 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $19 pack, 5,000 Credits, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/19-pack-5000-credits-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $3.80 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $79 pack, 25,000 Credits, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/79-pack-25000-credits-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $3.16 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $249 pack, 100,000 Credits, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/249-pack-100000-credits-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $2.49 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $899 pack, 500,000 Credits, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/899-pack-500000-credits-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $1.798 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $19 monthly, Starter, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/19-monthly-starter-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $1.90 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $49 monthly, Growth, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/49-monthly-growth-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $0.98 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $149 monthly, Scale, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/149-monthly-scale-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $0.596 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $182.04 yearly, Starter, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/182-04-yearly-starter-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $1.517 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $470.04 yearly, Growth, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/470-04-yearly-growth-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $0.783 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, $1,430.04 yearly, Scale, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/1430-04-yearly-scale-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): $0.477 per 1,000, 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)
- [KaijuVerifier, contact us, Enterprise, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/contact-us-enterprise-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt): 50% complete, stored (DNS valid, MX count, MX providers, MX grade: live)

## KaijuVerifier's calls (6)

- `POST /api/v1/jobs`, Submit an async bulk job: [KaijuVerifier, free, POST /api/v1/jobs, Submit an async bulk job](https://datacircle.dev/validate-email-apis/kaijuverifier/free-post-api-v1-jobs-submit-an-async-bulk-job/llms.txt)
- `POST /api/v1/jobs`, Submit an async bulk job with the SMTP probe: [KaijuVerifier, free, POST /api/v1/jobs, Submit an async bulk job with the SMTP probe](https://datacircle.dev/validate-email-apis/kaijuverifier/free-free-post-api-v1-jobs/llms.txt)
- `POST /api/v1/verify-batch`, Verify a batch synchronously: [KaijuVerifier, free, POST /api/v1/verify-batch, Verify a batch synchronously](https://datacircle.dev/validate-email-apis/kaijuverifier/free-post-api-v1-verify-batch-verify-a-batch-synchronously/llms.txt)
- `POST /api/v1/verify-batch`, Verify a batch synchronously with the SMTP probe: [KaijuVerifier, free, POST /api/v1/verify-batch, Verify a batch synchronously with the SMTP probe](https://datacircle.dev/validate-email-apis/kaijuverifier/free-free-post-api-v1-verify-batch/llms.txt)
- `POST /api/v1/verify-single`, Verify a single email (authenticated): [KaijuVerifier, free, POST /api/v1/verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/free-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt)
- `POST /api/v1/verify-single`, Verify a single email with the SMTP probe (authenticated): [KaijuVerifier, free, POST /api/v1/verify-single, Verify a single email with the SMTP probe (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/free-free-post-api-v1-verify-single/llms.txt)

## KaijuVerifier's APIs (1)

- [KaijuVerifier: email verification API pricing, 12 plans, verify-single, Verify a single email (authenticated)](https://datacircle.dev/validate-email-apis/kaijuverifier/free-post-api-v1-verify-single-verify-a-single-email-authenticated/llms.txt)

## KaijuVerifier: email verification API alternatives

- [Elastic Email, $189 monthly, Email API Pro (400,000 emails/month), POST /verifications/{email}](https://datacircle.dev/validate-email-apis/elastic-email/189-monthly-email-api-pro-400000-emails-month-post-verifications-email/llms.txt): $0.472 per 1,000, 50% complete, stored
- [IsItDisposable, $1,430 yearly, Pro, POST /v1/check](https://datacircle.dev/validate-email-apis/isitdisposable/1430-yearly-pro-post-v1-check/llms.txt): $0.477 per 1,000, 50% complete, stored
- [NexMailPro, $290 yearly, Pro, POST /verify/email](https://datacircle.dev/validate-email-apis/nexmailpro/290-yearly-pro-post-verify-email/llms.txt): $0.483 per 1,000, 50% complete, stored
- [ReefAPI, $450 quarterly](https://datacircle.dev/validate-email-apis/reefapi/450-quarterly/llms.txt): $0.50 per 1,000, 67% complete, stored

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-10-20.

- https://kaijuverifier.com/api-docs
- https://kaijuverifier.com/dashboard/billing
- https://kaijuverifier.com/email-verification-api
- https://kaijuverifier.com/legal/notice
- https://kaijuverifier.com/legal/terms
- https://kaijuverifier.com/openapi.json
- https://kaijuverifier.com/pricing