To use Android extensions, you'll need Firefox for Android. To explore Firefox for desktop add-ons, please visit our desktop site.

Log in

1,149 extensions found in Web Development

Filter results
Search results
  • Experiment Finder

    Experiment Finder

    Detect A/B testing and feature flag tools on any webpage: Optimizely, VWO, LaunchDarkly, Statsig, and 15 more.

    Alfredo

    30 users

  • CountDown

    CountDown

    Toolbar countdown timer with badge and desktop notification

    nehan

    30 users

  • CSSOverride

    CSSOverride

    Override any site's CSS with your own rules — saved per domain

    IDGAF_Fandom

    30 users

  • RSVP Reader

    RSVP Reader

    Rapid serial visual presentation reader with WPM control

    nexma

    30 users

  • TagInspect

    TagInspect

    Inspect HTML meta tags and score the SEO setup of any page

    omyjuk

    30 users

  • AgentMask

    AgentMask

    Randomize or spoof your browser User-Agent with one click

    dexter

    30 users

  • Shortcut Map

    Shortcut Map

    Quick reference for productivity keyboard shortcuts

    Myres Carmella

    30 users

  • HexRGB

    HexRGB

    Flip colors between HEX and RGB/HSL formats with picker

    jubair

    30 users

  • API Key Vault

    API Key Vault

    Store and copy API keys locally. Available in English, Traditional Chinese, and Simplified Chinese.

    Ricardo Gould

    30 users

  • Feature Flag Scanner

    Feature Flag Scanner

    Detect A/B testing and feature flag tools on any webpage: Optimizely, VWO, LaunchDarkly, Statsig, and 15 more.

    Alfredo

    30 users

  • CryptoHash

    CryptoHash

    Crypto hash calculator — SHA-256, SHA-512, SHA-1 from text

    Aexodi

    30 users

  • Clipboard Manager

    Clipboard Manager

    Save and browse your recent clipboard history

    Radko Lachlan

    30 users

  • Number Formatter

    Number Formatter

    Format numbers as currency percent scientific and more

    Viviette Elton

    30 users

  • SiteSchedule

    SiteSchedule

    Schedule site blocking — keep focus during your chosen work hours

    Shreya

    30 users

  • QuickFeed

    QuickFeed

    Quick RSS reader with feed management and unread count badge

    Kinnaman

    30 users

  • PG_Refresher

    PG_Refresher

    Refresh the website page based on your desired time.

    mohamad mansouri khojasteh

    30 users

  • WiFiVault

    WiFiVault

    Store Wi-Fi network names and passwords locally in an encrypted vault

    Jimmy Gessica

    30 users

  • Anim Inspector

    Anim Inspector

    Inspect CSS animation names duration and timing functions

    Padixow-

    30 users

  • StackOrder

    StackOrder

    Map every element's z-index on the current page and visualize the stacking order

    vuqik

    30 users

  • StorageView

    StorageView

    Inspect localStorage and sessionStorage of the current tab

    Teofila

    30 users

  • PX Ruler

    PX Ruler

    Overlay ruler tool to check sizes and spacing on page

    keser

    30 users

  • History Heatmap

    History Heatmap

    Visualize your browsing activity as a GitHub-style heatmap calendar. Click any day to see the sites you visited.

    Kaalas Daria

    30 users

  • Note MD

    Note MD

    Persistent markdown notebook with live preview toggle

    Margahara

    30 users

  • TimeBlock

    TimeBlock

    Block distracting websites during scheduled time windows

    Shreya

    30 users

  • Page Translator

    Page Translator

    Translate selected text using Google Translate API

    langta

    30 users