Email utilities
A focused collection of utilities for email users and developers. Choose an online address checker, add a template editor to a React product, or self-host email validity checks with a CLI and API—use only the tool you need.
Email resource library
These are independent utilities, not a bundled platform or required sequence. Start with the free online email checker, or choose an open-source project for template editing or self-hosted email verification.
Free online tool
Enter one email address and run a quick online check. No software installation, account, or local deployment is required.
Open source · React · MIT
A customizable React email template editor for building responsive transactional and marketing email.
Open source · Go · MIT
An open-source CLI and HTTP API for checking whether email addresses are valid and able to receive email.
Purpose-built utilities
There is no required order and no need to use every resource. Pick the utility that matches what you are trying to do today.
Use the free web tool when you want a quick check on one address without setting anything up.
Use the React component when your product needs an embeddable visual email editor.
Use smtp-probe when developers need to check email validity through a CLI or HTTP API.
A quick comparison based on the task, interface, and setup required.
Open source
Monto Email Builder and smtp-probe are separate MIT-licensed projects. Review the code, run either project in your own environment, adapt it to a specific use case, or contribute improvements upstream.
Inspect the implementation and understand how each verification or editor capability works.
Integrate either project into internal tools, products, or technical environments.
Adopt one component or verification tool without committing to a larger toolchain.
FAQ
The online email checker is available as a free browser-based tool. Monto Email Builder and smtp-probe are open-source projects released under the MIT license; review each repository for current installation and usage details.
Both tools check email validity. The free email checker is designed for a quick, single-address check in a browser. smtp-probe is an open-source CLI and HTTP API for developers who want to run or integrate email verification in their own environment.
Yes. Monto Email Builder is a React component library designed to be embedded in another React application. It supports visual editing, custom themes, image upload handling, change callbacks, and HTML or JSON output.
These resources help create templates and verify email addresses. For reliable production delivery, connect your application to uSpeedo Email API or SMTP Relay.
Need production email delivery?
These utilities handle specific tasks. For transactional or marketing email at scale, use uSpeedo Email API or SMTP Relay.