The playground

Try any of 919 endpoints — live.

Pick an endpoint, load a working example, tweak the params, and send — no signup to try. Results render the way the data deserves; raw JSON, headers & code are one tab away.

Playground demo key · api.reefapi.com

post/email-preflight/v1/css_support1 credit

Email-client CSS/HTML compatibility map for the template (Can-I-Email data, MIT): which CSS features used in the HTML break or degrade in Outlook/Gmail/Apple Mail/Yahoo and friends. Pure local compute (offline snapshot).

Working example

Parameters

htmlrequired

The full HTML of the email you are about to send (paste the source). Parsed read-only in a no-network, no-script sandbox.

request preview

curl -X POST https://api.reefapi.com/email-preflight/v1/css_support \
  -H "x-api-key: $REEF_KEY" \
  -H "content-type: application/json" \
  -d '{"html":"<div style='display:flex'>x</div>"}'

Hit Send to run this endpoint live.