Free email tools that run in your browser
Everything you need to check an email before it goes out — rendering, dark mode, contrast, subject-line truncation, spam signals and sender authentication. No signup, no usage limits.
All free email tools
Four questions every email has to answer
Most pre-send mistakes are not typos — they are a client that renders your email differently, an inbox that truncates it, or a domain that never authorised the send.
- 1
Does it render?
Gmail strips your <style> block, classic Outlook lays out on Word’s engine, Apple Mail respects the dark-mode CSS the other two ignore. The preview tool applies each engine’s documented limits and names every change.
- 2
Does it read well in the list?
Before anyone sees your design they see a sender, a subject and a snippet in a narrow column. The subject-line tool measures where each client cuts them, and flags a snippet that is scraped body text you never wrote.
- 3
Will it arrive at all?
Placement is decided mostly by authentication, reputation and engagement. The deliverability check reads your SPF, DKIM and DMARC records and hands you the exact TXT record to publish where one is missing.
What is free, and what needs an account
We would rather say this plainly than have you find the wall halfway through a check.
Free and ungated
- Every preview: desktop, mobile, landscape, 20 client lenses, per-client dark mode.
- Blocked-image rendering, the Gmail 102KB clip line, and the combinatorial state grid.
- Measured WCAG contrast, the read-aloud transcript, and the colour-vision lenses.
- Pixel-measured inbox rows for ten clients, plus subject and preheader findings.
- .eml parsing with inline images, and the SPF / DKIM / DMARC / BIMI / MTA-STS lookup.
Behind a free account
- The scored pre-send report — every check on one page, out of 100, printable.
- The SpamAssassin score, because it is the one check that sends your email to a third party (Postmark’s SpamCheck service) and has to be rate-limited to somebody.
- Sharing an email for review and approval, which is what Proofel actually is.
A free account costs nothing and needs no card. New accounts also get every paid feature free for 14 days.
Why we built these
Proofel is the review-and-approval layer for email campaigns. These tools are the checks we needed anyway.
Every one of these tools exists because it was already inside Proofel — the engines reviewers need to see what an email will really look like on a phone, in dark mode, with images blocked, with the subject cut short. None of that is worth hiding behind a signup: a tool you can only use after creating an account is a tool you use once.
The other reason is method. A screenshot service can show you that something broke but not why, because a PNG has pixels and no CSS. We keep the model, which is what lets us say “this caption passes at 7.1:1 as authored and fails at 3.8:1 once Gmail inverts the panel behind it” — and it also means we owe you a clear account of what a simulation cannot do. That has its own page, linked from every tool.
Free email tools, answered
- Are these email tools really free?
- Yes. Every preview, measurement and check on these pages is free, unlimited, and needs no account. The only thing behind a free account is the scored pre-send report and the SpamAssassin score, because that one check sends your email to a third-party service and we rate-limit it per account.
- Does my email get uploaded anywhere?
- Almost never. The previews, the client and dark-mode simulations, the contrast measurements, the .eml parsing and the inbox-row measurements all run inside your browser, so the HTML never leaves your machine. Two checks are explicit exceptions and say so on the page: the SpamAssassin score (sent to Postmark’s SpamCheck service when you click) and the deliverability check (which reads public DNS records for the domain you type).
- Do I need to install anything?
- No. There is no extension, no desktop app, and no test-send address to copy. Paste HTML or drop a file and the tool runs.
- How is this different from Litmus or Email on Acid?
- Those services render your email on real devices and hand you screenshots. We simulate deterministically instead: we keep the colour model and the CSS, so we can tell you a caption resolves to 4.19:1 once Gmail inverts your panel, or which exact line of CSS an Outlook version drops. A screenshot can show you a broken layout but cannot explain it, and we cannot promise a pixel-exact Word render. The tradeoff is written up in full on "How our simulation works".
- Can I use these tools on a client’s email?
- Yes, and nothing stops you doing it repeatedly. If you need the client to actually sign off on the email, that is what Proofel itself does: one link, comments and annotations pinned to the pixel, and an approval on the record — reviewers never need an account.
- Which email clients do the simulations cover?
- Twenty client, browser and OS combinations across Gmail, Outlook (including classic Outlook for Windows on the Word engine), Apple Mail, Yahoo, Samsung Mail and Thunderbird, each mapped to the engine that actually renders it. Dark mode is modelled separately for Apple Mail, Gmail and Outlook, because all three behave differently.
Checking is step one. Approval is the job.
When the email is right, share it for sign-off: one link, pinned feedback, and every approval on the record. Reviewers never need an account.
14-day all-access trial · no credit card required · reviewers never need an account