MailHog vs MailSlurp

MailHog is a free email testing tool for developers. Applications send mail to it over SMTP, after which users can inspect messages in a web interface or retrieve them through a JSON API. The interface displays plain text, HTML or source, supports encoded headers and updates in real time. The API can list, retrieve and delete messages, and download complete messages or individual MIME parts. Messages may also be released to real SMTP servers. MailHog supports ESMTP RFC5321, SMTP AUTH and PIPELINING, and includes a Chaos Monkey feature for failure testing. Storage defaults to memory, with MongoDB and Maildir also available. It can run from the command line, as a daemon, in Docker or on AWS Elastic Beanstalk. Its default SMTP and HTTP ports are 1025 and 8025. In-memory storage limits Elastic Beanstalk deployments to one instance; load-balanced deployments require MongoDB-backed storage. MailHog is released under the MIT license.

MailSlurp provides tools to build, test, and automate email and SMS workflows. Users can create temporary or permanent inboxes and handle messages through APIs, SDKs, SMTP, IMAP, and webhooks. It supports end-to-end tests for scenarios including OTP, MFA, magic links, and load testing, as well as device previews, email audits, and inbox placement checks. Pipelines can route messages and attachments using webhooks, forwarding, and automatic replies. AI extraction can turn emails and attachments such as PDFs and images into structured JSON using prompts, schemas, and OCR. Listed integrations include Playwright, Cypress, Selenium, HubSpot, Braze, Mailchimp, Zapier, and AI assistants through MCP. A REST API and official SDKs cover several programming languages. The free plan has capped allowances, including 500 received emails and 1,000 sandbox sends per month. Starter costs $19.99/mo; custom domains and phone numbers require Pro on Free and Starter plans. MailSlurp is web- and API-accessible.