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smtp4dev vs Mailtrap: catalog facts
smtp4dev	Mailtrap
Free Free to download, with the source code published on GitHub.	Freemium Self-serve sign-up with published pricing for paid tiers.
Web, Self-hosted	Web
Captures outgoing email so test messages never reach real inboxes Web interface for inspecting captured messages	Captures test emails without reaching real inboxes Previews rendering across 100+ email clients and devices
Meant for development and testing, not for sending real mail Documentation lives mainly in the repository	Hosted service only Much of the product focuses on sending email rather than testing
Downloadable app, Self-hosted	Web application, Hosted service
Closed source	Closed source
License not stated	License not stated
No account needed	Account needed
Works offline	Needs internet
Official website Full listing and sources Checked October 2, 2026	Official website Full listing and sources Checked October 2, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.