Email APIs
Free email APIs: address validation and verification, transactional sending with free tiers, disposable and temporary inbox services, and inbox testing tools.
8 tested APIs with full docs · 8 need no key · 37 more listed
Tested, with full documentation
We called each of these before publishing. Every page carries a working curl command, the real JSON response it returned, parameters and common errors.
AGPC Domain Check
Free email authentication API with no key: grades a domain's SPF, DKIM, DMARC and MX setup and lists the concrete gaps it found. Tested example included.
DeBounce Disposable Check
Free disposable-email check with no key: pass an address, get back a single boolean saying whether the domain is a throwaway provider. Tested example included.
Disposable Email Domains List
Free JSON array of roughly a hundred thousand disposable email domains, rebuilt daily from dozens of upstream sources. No key, permissive CORS. Tested example included.
Gravatar Avatars
Free avatar image API with no key: hash an email address, request a URL, get a PNG back. Configurable size and automatic fallbacks. Tested example included.
Guerrilla Mail
Free disposable email API with no key: create a temporary inbox and read incoming messages programmatically. Useful for testing signup flows. Tested.
Mail.tm
Free disposable email API with no key: create temporary inboxes programmatically and read incoming messages. Ideal for testing signup flows. Tested.
Mailcheck.ai
Free email validation API with no key: check format, MX records, domain age and whether an address is disposable, in a single request. Tested example.
Temp Mail (temp-mail.io) Domains
Free read-only endpoint listing every domain temp-mail.io currently offers for throwaway inboxes, with forwarding limits. No key. Tested example included.
Choosing between these Email APIs
Email APIs do three distinct jobs: validating that an address is real and deliverable, actually sending mail, and providing throwaway inboxes for testing signup flows.
Validation APIs are the most useful of the three for reducing bounce rates at signup. Be careful with disposable-inbox services — they are for testing, and using them to bypass verification on real services usually breaks terms of use.
More Email APIs in the directory
37 further APIs in this category, of which 6 need no API key. These are catalogued from the public-API lists and link straight to each provider's own documentation — we have not tested them yet, so treat the auth and CORS flags as the upstream list's claim rather than ours. They are promoted to a full tested page as we work through them.
| API | What it does | Auth |
|---|---|---|
| Abstract Email Validation | Validate email addresses for deliverability and spam | KeyCORS |
| Academic Email API | This API allows you to verify whether an email belongs to a recognized educational institution | KeyCORS |
| Atomic Mail | Email for AI agents: programmatic inbox creation and send/receive over JMAP | Key |
| Atomic Mail | Email for AI agents with programmatic inbox creation and send/receive over the open JMAP standard | Key |
| Cloudmersive Validate | Validate email addresses, phone numbers, VAT numbers and domain names | KeyCORS |
| Disify | Validate and detect disposable and temporary email addresses | NoneCORS |
| DropMail | GraphQL API for creating and managing ephemeral e-mail inboxes | None |
| Email Validation | Validate email addresses for deliverability and spam | KeyCORS |
| EmailJS | Send emails directly from client-side JavaScript without a backend server | KeyCORS |
| Emailvalidation | E-Mail address validation | KeyCORS |
| Enveloop | Design, host, and send emails and texts. All from one place - with a simple API | KeyCORS |
| EVA | Validate email addresses | NoneCORS |
| FreeCustom.Email | Disposable email inboxes with OTP extraction and real-time WebSocket events | KeyCORS |
| Heybounce | Email Verification API | NoneCORS |
| ImprovMX | API for free email forwarding service | Key |
| IndiePitcher | Everything email for your startup with markdown support | KeyCORS |
| Kickbox | Email verification API | NoneCORS |
| Kiprio Email Validate | Free email validation: MX check, disposable detection, syntax | KeyCORS |
| mail.gw | 10 Minute Mail | NoneCORS |
| mailboxlayer | Email address validation | Key |
| MailboxValidator | Validate email address to improve deliverability | Key |
| Mailtrap | Email API and SMTP for sending transactional and bulk emails, with email testing sandbox for safe development | Key |
| Mailtrap | A service for the safe testing of emails sent from the development and staging environments | Key |
| NoParam | Email validation API for real-time & bulk checking | Key |
| Notilify | A seamless messaging platform & API to send all types of SMS | KeyCORS |
| PostStack | EU-hosted email API for transactional and marketing email, with contacts, broadcasts, and analytics | Key |
| Proweblook Email Checker | Validate email addresses without sending | KeyCORS |
| Resend | Email API for developers | KeyCORS |
| Sendgrid | A cloud-based SMTP provider that allows you to send emails without having to maintain email servers | Key |
| Sendinblue | A service that provides solutions relating to marketing and/or transactional email and/or SMS | Key |
| Sweego | Self-serve multichannel notification platform for transactional email, SMS, push web& mobile, chat, in-app | KeyCORS |
| Sweep Emails | Reliable email validation API with Free tier | Key |
| Temporary and Disposable emails API | This API provides temporary & disposable email addresses | KeyCORS |
| Trueguard | Trueguard offers API for detecting temporary emails, free-tier abusers and automated bots | Key |
| uchecker | Bulk email verification with full SMTP server responses | Key |
| Verifier | Verifies that a given email is real | KeyCORS |
| Zyntra | Unlimited e-mail inboxes with API access. Catch OTPs, reset links, and sign-up emails in test flows | Key |