Gmail is the strictest of the major clients, and the one most likely to break a design that looked fine in the browser. Paste your HTML below and we render it in a real, logged-in Gmail account — then screenshot exactly what a recipient sees.
…or drop a .eml file onto the box, or .
Rendered in Blink, in a real logged-in Gmail session — never an engine approximation, so what you see is what the recipient gets.
flexbox, grid, position, box-shadow and animations are removed outright, so layouts that rely on them collapse to stacked blocks.
images are re-served through Google's proxy, which changes caching and breaks tracking pixels that expect a direct hit.
past roughly 102KB Gmail truncates the message and shows a “View entire message” link, hiding anything below the cut.
Every route below renders in Gmail. Drop the clients field and you get every live client instead.
Use the box above. Nothing to install, and the preview opens as soon as the render finishes.
POST to /v1/jobs with "clients": ["gmail"], then poll for the screenshot. Works from any language.
A hosted endpoint at /v1/mcp. Point Claude Code, Claude Desktop or Cursor at it and call submit_preview with gmail.
An agent skill doc at /v1/skills.md — point your agent at it and it knows the whole workflow.
# Render this email in Gmail (Web) only curl -X POST https://api.powerline.ai/v1/jobs \ -H "Content-Type: application/json" \ -d '{ "html": "<html>…</html>", "subject": "Welcome aboard", "clients": ["gmail"] }' # -> { "job_id": "j_…", "poll_url": "/v1/jobs/j_…" } # poll that until status is "completed", then read results.renders[]
Each client strips different CSS. The same HTML can look right in one and break in another, so it is worth checking the rest.
Outlook on the web renders very differently from the desktop client, and differently again from Gmail — spacing and positioning are where it bites. Preview in Outlook →
Yahoo Mail is the one people skip — and the one that most often surprises them, because its inbox sorts mail before the recipient ever opens it. Preview in Yahoo Mail →