Experimental

For a given set of browsers what APIs are still considred experimental, and how long have they been experimental?

Example Comparisons
Browsers
Features

Summary

Experimental APIs

Below is a list of features that are marked as "Experimental" in Firefox and Safari

Raw Data

Quick Links:

HTTP Data

API First Browser Date Last Browser Date Days in experimentation Notes
http.headers.Content-Security-Policy.script-src.inline-speculation-rules Safari12/12/2025 97
http.headers.Content-Security-Policy.script-src.trusted-types-eval 📋Safari9/15/2025 185
http.headers.Early-Data 📋Firefox1/23/2018 2977
http.headers.Idempotency-Key 📋Firefox2/4/2025 408
Firefox: Automatically adds a unique 64-bit key for POST requests when needed, if not set in JavaScript.
http.headers.Integrity-Policy.blocked-destinations_style 📋Firefox8/19/2025 212
http.headers.Integrity-Policy-Report-Only.blocked-destinations_style 📋Firefox8/19/2025 212
http.headers.Sec-GPC 📋Firefox11/21/2023 849
Firefox: Opt-in to GPC using the Website Privacy Preference setting (about:preferences#privacy) checkbox 'Tell websites not to sell or share my data', or by setting the preference privacy.globalprivacycontrol.enabled to true.Firefox for Android: Opt-in to GPC using the Enhanced Tracking Protection toggle 'Tell web sites not to share & sell data', or by setting the preference privacy.globalprivacycontrol.enabled to true.
http.headers.Sec-Purpose.speculationrules Safari12/12/2025 97
http.headers.Sec-Speculation-Tags 📋Safari12/12/2025 97
http.headers.Speculation-Rules 📋Safari12/12/2025 97