# isBusinessEmail, free (tier 0), POST /v1/check: Email verification API

> Know if a signup is a work email, and whether their company runs Google Workspace or Microsoft 365. Free API, with the reasons behind every verdict.

isBusinessEmail's email verification API on its Free (tier 0) plan. It costs $0.00 per 1,000 emails. It returns 4 of the 6 key fields we check: Address, Deliverability, Confidence, Company.
We ran isBusinessEmail in [our email verification API benchmark](https://datacircle.dev/best-email-verification-api.txt). We didn't score any isBusinessEmail plan.
This plan is free. We rank 3,886 plans for email verification APIs by price. Half the plans cost $1.998 per 1,000 emails or less.
[treg's top-up from $10](https://datacircle.dev/validate-email-apis/treg/top-up-from-10/llms.txt) is the cheapest paid plan per 1,000 emails: $0.00 on average. treg asks one provider after another until one answers. You pay $68.365 per 1,000 emails when no provider answers.
[Disify's $9 monthly plan (/email)](https://datacircle.dev/validate-email-apis/disify/9-monthly-starter-post-email/llms.txt) covers any number of emails. Disify's $9 monthly plan costs less up front than treg's top-up from $10.
[email-validation.org](https://datacircle.dev/validate-email-apis/email-validation-org/450-pack-1000000-credits-post-v1-validate/llms.txt), [pingutil](https://datacircle.dev/validate-email-apis/pingutil/free-api-key-post-v1-verify/llms.txt) and [MailTester Ninja](https://datacircle.dev/validate-email-apis/mailtester-ninja/23-99-monthly/llms.txt) are the best email verification API providers in the Datacircle benchmark.

- This page: https://datacircle.dev/validate-email-apis/isbusinessemail/free-tier-0-post-v1-check
- [Email validation API: 180+ verification providers compared](https://datacircle.dev/best-email-verification-api.txt)
- Get it: https://isbusinessemail.com/docs/rate-limits?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- Request: `POST https://api.isbusinessemail.com/v1/check`
- API key: with the plan, on https://isbusinessemail.com/docs/rate-limits?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- Its API docs: https://isbusinessemail.com/docs/check-endpoint?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- Sold by: isBusinessEmail (https://isbusinessemail.com?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing)
- Checked: 2026-11-05

## In the answer

- Completeness: 67%
- Address: ✓
- Deliverability: ✓
- Confidence: ✓
- Company: ✓

## Price

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

## Aggregators

- Aggregators: none

## Charges

- Extra fields: domain age, new domain: +$0.00
- Also pays for: from the same budget: Batch checks · Verify that a mailbox exists

## Overage

- Units cap: hard

## Not found

- $ per 1,000: $0.00

## Catch-all

- $ per 1,000: $0.00

## In their words

- Their pitch: Know if a signup is a work email, and whether their company runs Google Workspace or Microsoft 365. Free API, with the reasons behind every verdict.

## Data

- What it checks: format, mail servers, disposable domains, role addresses
- Keep data: no limit
- Use data: You must not, and must not help anyone else to: resell, sublicense, rent or wrap the API (or its output) as a paid or free product or service whose main value is our data or verdicts, without our written permission, scrape, sweep or bulk-harvest our data, lists or verdicts, including systematically checking domains or addresses to rebuild our dataset, use the Service for spam, list-washing or cleaning lists of addresses you don't have a lawful basis to email, get around limits or protections, including rotating keys, accounts, IP addresses or networks, automating the public checker, or bypassing robot protection, create multiple accounts to evade quotas or suspensions, probe, scan or test the Service's security except as allowed in our security policy, interfere with the Service or other users, or overload our infrastructure, use the Service unlawfully, including in breach of data protection law, or to discriminate unlawfully against people, submit special categories of personal data or anything other than email addresses and domains you're checking.

## Plan

- Pay: $0
- You get: 100 results a day
- Enough for: 100 calls a day

## Rate limit

- Per second: 5
- Concurrent: 10
- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: one of email, domain or url, Content-Type header "application/json". Optional: policy, deep, workspace
- Method: POST
- Path: /v1/check

## About the plan

- Plan: Free (tier 0)
- Who can get it: anyone aged 16 or over, with an account

## The 47 fields the plan's answer can hold

email, URL, normalized email, domain, business email, category, confidence, recommendation, policy, free provider, disposable, relay, role account, shared inbox confidence, shared inbox match, group confidence, group match, blocked, lookalike, subaddress, did you mean, has MX record, mail provider, MX records, SPF record, DMARC policy, Google Workspace detected, Google Workspace evidence, Microsoft 365 detected, Microsoft 365 tenant ID, Microsoft 365 tenant region, Microsoft 365 auth, Microsoft 365 identity provider, Microsoft 365 evidence, other suite, workspace pending, mailbox provider, mailbox gateway, mailbox confidence, mailbox evidence, Google Workspace ready, Microsoft 365 ready, reasons, degraded, cached, time taken, request ID

## isBusinessEmail's plans (4)

- [isBusinessEmail, free (tier 0), POST /v1/check](https://datacircle.dev/validate-email-apis/isbusinessemail/free-tier-0-post-v1-check/llms.txt): $0.00 per 1,000, 67% complete
- [isBusinessEmail, contact us, Paid (tier 1), POST /v1/check](https://datacircle.dev/validate-email-apis/isbusinessemail/contact-us-paid-tier-1-post-v1-check/llms.txt): 67% complete
- [isBusinessEmail, contact us, Paid (tier 2), POST /v1/check](https://datacircle.dev/validate-email-apis/isbusinessemail/contact-us-paid-tier-2-post-v1-check/llms.txt): 67% complete
- [isBusinessEmail, contact us, Paid (tier 3), POST /v1/check](https://datacircle.dev/validate-email-apis/isbusinessemail/contact-us-paid-tier-3-post-v1-check/llms.txt): 67% complete

## isBusinessEmail's calls (3)

- `POST /v1/check/batch`: [isBusinessEmail, free (tier 0), POST /v1/check/batch](https://datacircle.dev/validate-email-apis/isbusinessemail/free-tier-0-post-v1-check-batch/llms.txt)
- `POST /v1/check`: [isBusinessEmail, free (tier 0), POST /v1/check](https://datacircle.dev/validate-email-apis/isbusinessemail/free-tier-0-post-v1-check/llms.txt)
- `POST /v1/verify`: [isBusinessEmail, free (tier 0), POST /v1/verify](https://datacircle.dev/validate-email-apis/isbusinessemail/free-tier-0-post-v1-verify/llms.txt)

## isBusinessEmail's APIs (1)

- [isBusinessEmail: email verification API pricing, 4 plans, POST /v1/check](https://datacircle.dev/validate-email-apis/isbusinessemail/free-tier-0-post-v1-check/llms.txt)

## isBusinessEmail: email verification API alternatives

- [email-validation.org, free credits, POST /v1/validate](https://datacircle.dev/validate-email-apis/email-validation-org/free-credits-post-v1-validate/llms.txt): $0.00 per 1,000, 50% complete, stored
- [pingutil, free API key, POST /v1/verify](https://datacircle.dev/validate-email-apis/pingutil/free-api-key-post-v1-verify/llms.txt): $0.00 per 1,000, 50% complete, 30 days
- [MailTester Ninja, free, No token](https://datacircle.dev/validate-email-apis/mailtester-ninja/free-no-token/llms.txt): $0.00 per 1,000, 50% complete, live
- [Enrich.so, free, POST /email-validation](https://datacircle.dev/validate-email-apis/enrich-so/free/llms.txt): $0.00 per 1,000, 50% complete, live
- [Fideo, free](https://datacircle.dev/validate-email-apis/fideo/free/llms.txt): $0.00 per 1,000, 33% complete

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-11-05.

- https://api.isbusinessemail.com/openapi.json?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://isbusinessemail.com/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://isbusinessemail.com/docs/check-endpoint.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://isbusinessemail.com/docs/rate-limits?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://isbusinessemail.com/docs/rate-limits.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://isbusinessemail.com/docs/response-fields.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://isbusinessemail.com/terms?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing