# UniOne, free, POST /email-validation/single.json: Email verification API

> Avoid sending emails to non-valid email addresses with UniOne’s email validation API tool. Integrate it easily and take care of your deliverability and sender reputation by checking the validity of email addresses before adding them to your lists.

UniOne'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, Company.
We rank 3,215 plans by price. [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.
[MailTester Ninja](https://datacircle.dev/validate-email-apis/mailtester-ninja/23-99-monthly/llms.txt), [Enrich.so](https://datacircle.dev/validate-email-apis/enrich-so/499-monthly/llms.txt) and [GetProspect](https://datacircle.dev/validate-email-apis/getprospect/369-pack/llms.txt) are the best email verification API providers in our benchmark.

- This page: https://datacircle.dev/validate-email-apis/unione/free-post-email-validation-single-json
- [Best email verification API in 2026: providers compared](https://datacircle.dev/best-email-verification-api.txt)
- Get it: https://unione.io/en/pricing/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- Request: `POST https://api.unione.io/en/transactional/api/v1/email-validation/single.json`
- API key: with the plan, on https://unione.io/en/pricing/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- Its API docs: https://docs.unione.io/en/web-api-ref?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing#email-validation-single
- Sold by: UniOne (https://unione.io?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing)
- Checked: 2026-11-03

## In the answer

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

## Price

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

## Aggregators

- Aggregators: none

## Charges

- Also pays for: email-send (100 emails a day)

## Not found

- $ per 1,000: $0.00

## In their words

- Their pitch: Avoid sending emails to non-valid email addresses with UniOne’s email validation API tool. Integrate it easily and take care of your deliverability and sender reputation by checking the validity of email addresses before adding them to your lists.

## Data

- Freshness: live
- What it checks: format, mail servers, disposable domains, role addresses, mailbox
- Keep data: no limit
- Use data: You may use the Services for commercial purposes only [...] You may not share API tokens to exceed UniOne's rate limitations. You may not use the UniOne API for spamming purposes.

## Plan

- Pay: $0
- You get: 5 requests a month
- Enough for: 5 calls a month

## Rate limit

- Concurrent: 2
- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: email
- Method: POST
- Path: /email-validation/single.json

## About the plan

- Plan: Free
- Who can get it: anyone, a company or a person 18 or older, using the service for commercial purposes, needs no credit card

## The 11 fields the plan's answer can hold

status, email address, result, cause, validity, local part, domain, MX found, MX record, did you mean, processed at

## UniOne's plans (23)

- [UniOne, free, POST /email-validation/single.json](https://datacircle.dev/validate-email-apis/unione/free-post-email-validation-single-json/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, free trial](https://datacircle.dev/validate-email-apis/unione/free-trial/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $4 monthly, StartUp 6K, 6,000 emails a month, first 100 validations a month](https://datacircle.dev/validate-email-apis/unione/4-monthly-startup-6k-6000-emails-a-month-first-100-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $6 monthly, Standard, 10,000 emails a month, first 100 validations a month](https://datacircle.dev/validate-email-apis/unione/6-monthly-standard-10000-emails-a-month-first-100-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $11 monthly, Standard, 20,000 emails a month, first 100 validations a month](https://datacircle.dev/validate-email-apis/unione/11-monthly-standard-20000-emails-a-month-first-100-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $25 monthly, Standard, 50,000 emails a month, first 100 validations a month](https://datacircle.dev/validate-email-apis/unione/25-monthly-standard-50000-emails-a-month-first-100-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $40 monthly, Standard, 100,000 emails a month, first 6,000 validations a month](https://datacircle.dev/validate-email-apis/unione/40-monthly-standard-100000-emails-a-month-first-6000-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $75 monthly, Standard, 150,000 emails a month, first 6,000 validations a month](https://datacircle.dev/validate-email-apis/unione/75-monthly-standard-150000-emails-a-month-first-6000-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $150 monthly, Standard, 300,000 emails a month, first 6,000 validations a month](https://datacircle.dev/validate-email-apis/unione/150-monthly-standard-300000-emails-a-month-first-6000-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $300 monthly, Standard, 700,000 emails a month, first 6,000 validations a month](https://datacircle.dev/validate-email-apis/unione/300-monthly-standard-700000-emails-a-month-first-6000-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $600 monthly, Standard, 1,500,000 emails a month, first 6,000 validations a month](https://datacircle.dev/validate-email-apis/unione/600-monthly-standard-1500000-emails-a-month-first-6000-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $850 monthly, Standard, 3,000,000 emails a month, first 6,000 validations a month](https://datacircle.dev/validate-email-apis/unione/850-monthly-standard-3000000-emails-a-month-first-6000-validations-a-month/llms.txt): $0.00 per 1,000, 50% complete, live
- [UniOne, $4 monthly, StartUp 6K, 6,000 emails a month, from the 101st validation a month](https://datacircle.dev/validate-email-apis/unione/4-monthly-startup-6k-6000-emails-a-month-from-the-101st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $6 monthly, Standard, 10,000 emails a month, from the 101st validation a month](https://datacircle.dev/validate-email-apis/unione/6-monthly-standard-10000-emails-a-month-from-the-101st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $11 monthly, Standard, 20,000 emails a month, from the 101st validation a month](https://datacircle.dev/validate-email-apis/unione/11-monthly-standard-20000-emails-a-month-from-the-101st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $25 monthly, Standard, 50,000 emails a month, from the 101st validation a month](https://datacircle.dev/validate-email-apis/unione/25-monthly-standard-50000-emails-a-month-from-the-101st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $40 monthly, Standard, 100,000 emails a month, from the 6,001st validation a month](https://datacircle.dev/validate-email-apis/unione/40-monthly-standard-100000-emails-a-month-from-the-6001st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $75 monthly, Standard, 150,000 emails a month, from the 6,001st validation a month](https://datacircle.dev/validate-email-apis/unione/75-monthly-standard-150000-emails-a-month-from-the-6001st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $150 monthly, Standard, 300,000 emails a month, from the 6,001st validation a month](https://datacircle.dev/validate-email-apis/unione/150-monthly-standard-300000-emails-a-month-from-the-6001st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $300 monthly, Standard, 700,000 emails a month, from the 6,001st validation a month](https://datacircle.dev/validate-email-apis/unione/300-monthly-standard-700000-emails-a-month-from-the-6001st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $600 monthly, Standard, 1,500,000 emails a month, from the 6,001st validation a month](https://datacircle.dev/validate-email-apis/unione/600-monthly-standard-1500000-emails-a-month-from-the-6001st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, $850 monthly, Standard, 3,000,000 emails a month, from the 6,001st validation a month](https://datacircle.dev/validate-email-apis/unione/850-monthly-standard-3000000-emails-a-month-from-the-6001st-validation-a-month/llms.txt): $2.00 per 1,000, 50% complete, live
- [UniOne, contact us](https://datacircle.dev/validate-email-apis/unione/contact-us/llms.txt): 50% complete, live

## UniOne's calls (1)

- `POST /email-validation/single.json`: [UniOne, free, POST /email-validation/single.json](https://datacircle.dev/validate-email-apis/unione/free-post-email-validation-single-json/llms.txt)

## UniOne's APIs (1)

- [UniOne: email verification API pricing, 23 plans](https://datacircle.dev/validate-email-apis/unione/free-post-email-validation-single-json/llms.txt)

## UniOne: email verification API alternatives

- [Verimail, $20 pack](https://datacircle.dev/validate-email-apis/verimail/20-pack/llms.txt): $2.00 per 1,000, 50% complete, live
- [Verifly, $10 pack, Starter, POST /verify/bulk](https://datacircle.dev/validate-email-apis/verifly/10-pack-starter-post-verify-bulk/llms.txt): $2.00 per 1,000, 33% complete, live
- [MillionPhones, $60 monthly](https://datacircle.dev/validate-email-apis/millionphones/60-monthly/llms.txt): $2.00 per 1,000, 33% complete, live
- [NullBounce, $10 pack](https://datacircle.dev/validate-email-apis/nullbounce/10-pack/llms.txt): $2.00 per 1,000, 33% complete, live
- [SilverLining, pay as you go](https://datacircle.dev/validate-email-apis/silverlining/pay-as-you-go/llms.txt): $2.00 per 1,000, 33% complete, live

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-11-03.

- https://docs.unione.io/en/mcp?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://docs.unione.io/en/web-api-ref?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://docs.unione.io/llms-full.txt?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://unione.io/en/email-validation/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://unione.io/en/pricing/?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://unione.io/en/terms?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing
- https://unione.io/pricing.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=email-verification-api-pricing