Enterprise email testing platform
Litmus is a comprehensive email testing and analytics platform used by large enterprises. It offers email rendering previews across 100+ clients, spam testing, and analytics. After its 2025 acquisition by Validity, Litmus discontinued its $99 Basic plan. Pricing now starts at around $500/month for the Core plan.
Email testing, rendering and pre-deployment platform
Email on Acid (sometimes written "emailonacid" or "EoA") is an email testing and pre-deployment platform owned by Sinch. It provides previews across 90+ email clients, accessibility checks, spam testing, link validation, and a campaign precheck workflow. Email on Acid is no longer sold on its own: starting June 2026, customers are being moved to Mailgun Inspect, a usage-based QA suite. Inspect's Basic plan is $99/month for 1,000 previews and covers previews only; the accessibility, spam, link, image and code checks Email on Acid users rely on need Premium at $199/month for 2,000 previews, with $0.15 for each preview over the cap.
Usage-based email QA suite replacing Email on Acid
Mailgun Inspect is the email QA suite that Email on Acid customers are being migrated to starting June 2026, with annual and contract customers moving at the end of their current term. It keeps the core QA tools (email previews, accessibility checks, spam analysis, link and image validation, code analysis) but switches to usage-based pricing with no free plan: after a 30-day free trial, Basic is $99/month for 1,000 previews and covers previews only, while Premium is $199/month for 2,000 previews plus the QA checks, with $0.15 for each preview over the cap. Commenting and ESP integrations are on Mailgun's 2026 roadmap but had not shipped as of September 2026. For many Email on Acid customers, the forced migration is the natural moment to re-check what they actually use and what it now costs.
Email template builder and editor
Stripo is a drag-and-drop email template builder with HTML editing, a large template library, AMP support and one-click export to 90+ ESPs, CRMs and email clients. Its testing tool adds spam and accessibility checks and inbox previews powered by Email on Acid, though the previews are capped at 2 tests a month on the Basic and Medium plans and 3 on Pro. It focuses on creating emails, with testing built around the editor.
Email and landing page builder
RGE Studio is the drag-and-drop email and landing page builder previously called Beefree (BEE). Beefree renamed the app after its Really Good Emails brand on May 14, 2026, and its pricing now lives at reallygoodemails.com; the Beefree SDK for developers continues as a separate product. RGE Studio offers templates, synced rows, brand kits, content locking, Smart Check warnings for accessibility and Gmail clipping, and one-click export to about 25 ESPs and marketing platforms. It has no built-in previews on real email clients.
Collaborative email builder
Chamaileon is a collaborative email builder for enterprise teams, made by EDMdesigner. Teams build from reusable, lockable blocks and 100+ templates, edit the same email together in real time, invite guest reviewers to comment and approve, and sync approved emails to 18 ESPs and marketing platforms, including Braze, Iterable, Marketo, Eloqua and Klaviyo. Plans start at $400 a month, or about $4,000 a year, with no free plan listed. It has no built-in previews on real email clients.
Built-in Mailchimp preview tools
Mailchimp's built-in preview features let you preview emails across devices and send test emails. It's included with your Mailchimp account.
Email proofing and approval with simulated client previews
Proofel is an email proofing and approval tool. Teams bring an email in by forwarding it to a dedicated inbox address or uploading a .eml file, then reviewers pin comments, move it through a Kanban pipeline and approve it, without needing an account. It previews emails through simulated "lenses" for about 20 email clients, and its paid plans add a pre-send report with a support matrix, Outlook lint, contrast checks and SpamAssassin scoring. Pro is $15/month billed annually ($19 month to month); a free plan covers 3 active emails.
Email campaign proofing and approval for marketing teams
ProofJump is an email proofing and approval platform. Teams add a campaign as images or HTML or send a test from their ESP, and stakeholders open a unique link to leave point-and-click annotations and approve, with no login. It supports dynamic content variations and multi-language campaigns and lists integrations with Marketo, Eloqua, Salesforce, Mailchimp and others. Plans run from $49/month (Standard: 25 proofs, 1 user) to $199/month (Pro: 100 proofs, 10 users), with a 21-day free trial.
Email testing API with inboxes, deliverability checks and device previews
MailSlurp is an email and SMS testing platform for developers and QA teams. It provides disposable inboxes and an API to send, receive and assert on email in automated tests, plus inbox placement (deliverability) tests, warm-up senders and device previews across clients such as Gmail, Outlook, Yahoo and Apple Mail. Device previews are metered: 1 render a month on the free plan, 5 on Starter ($19.99/month), 10 on Pro ($49.99/month) and 200 on Growth ($129.99/month), with extra renders at $0.50 each on Pro and Growth.
| Tool | Starting Price | Best For | Guest Access |
|---|---|---|---|
| EmailQA | Free | Feedback & approvals | Yes |
| Litmus | $500+/month (Core); Enterprise custom | Large enterprises needing email client rendering t... | Requires account |
| Email on Acid | $99–$199/month + usage (Mailgun Inspect) | Enterprise email teams needing pre-deployment QA a... | Account needed (unlimited users) |
| Mailgun Inspect | $99–$199/month + usage | Email on Acid customers keeping the full pre-deplo... | Account needed (unlimited users) |
| Stripo | Free–$125/month; Prime custom | Teams needing to build emails from scratch with dr... | Requires account |
| Beefree (now RGE Studio) | Free–$160/month; Enterprise custom | Designers building emails and landing pages from s... | Not listed |
| Chamaileon | $400+/month | Larger teams needing real-time collaborative email... | Yes |
| Mailchimp Preview | Included with Mailchimp | Quick self-reviews when you don't need external fe... | Need Mailchimp account |
| Proofel | Pro $19/month ($15 billed annually); Team $49/month ($39 billed annually) | Budget-conscious teams that want a review pipeline... | Yes |
| ProofJump | $49–$199/month; Custom | Enterprise email teams proofing dynamic-content an... | Yes |
| MailSlurp | Free–$129.99/month; Enterprise custom | Developers and QA teams testing transactional emai... | Not listed |