# Word Replacer: Rules & Regex > Replace any word or phrase on any website with your own rules. Literal or regex matching, smart case preservation, whole-word boundaries and per-site scoping. Import and export as JSON or CSV. Nothing leaves your machine. Canonical page: [https://chrome-stats.com/d/word-replacer-rules-regex](https://chrome-stats.com/d/word-replacer-rules-regex) ## Overview - **ID:** `word-replacer-rules-regex` - **Platform:** Firefox - **Type:** Firefox add-on - **Status:** Available - **Publisher:** Fortress - **Category:** language-support - **Daily users:** 1 - **Version:** 1.0.1 - **Last updated:** 2026-08-05 - **First published:** 2026-08-02 - **Size:** 128 KB - **Data as of:** 2026-09-12 - **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/word-replacer-rules-regex/) - **Website:** [https://github.com/DerMaxiAufGit/Word-Replacer-Extension/issues](https://github.com/DerMaxiAufGit/Word-Replacer-Extension/issues) ## Description <p><strong>Word Replacer</strong> rewrites words and phrases on the pages you visit, using rules you write. Swap jargon for plain language, rename things you'd rather not read, fix a term a site always gets wrong, or translate recurring phrases — on every site, or only the ones you pick.</p> <h3>Matching</h3> <ul> <li><strong>Literal or regular expression</strong> — plain text for everyday swaps, full regex with capture groups ($1, $&) when you need them.</li> <li><strong>Smart case preservation</strong> — one rule handles every form. "dog → cat" turns DOG into CAT and Dog into Cat, without three separate rules.</li> <li><strong>Whole-word matching</strong> that understands accents and non-Latin scripts. "naive" will not match inside "naiveté" — it uses Unicode boundaries rather than the usual ASCII-only word break.</li> <li><strong>Case sensitivity</strong> per rule, not as a global setting.</li> </ul> <h3>Rules that don't fight each other</h3> <p>Every rule is matched against the original text, and overlaps are resolved by priority. A rule turning "a" into "b" alongside one turning "b" into "c" leaves "a b" as "b c" — never "c c". Most replacers apply rules one after another and quietly produce the wrong answer here. Drag rules to set which wins.</p> <h3>Scoping</h3> <p>Limit any rule to specific sites or exclude it from them, with wildcard patterns like *.example.com. There's a global site blocklist, and a one-click pause for the site you're on.</p> <h3>Import and export</h3> <p>Move rules between machines or share a set with someone else. JSON and CSV both work, and importing shows you a preview — how many rules are new, how many are duplicates, what's invalid — before anything is written. Three merge strategies, and an undo that puts back exactly what you had.</p> <h3>Careful with your pages</h3> <ul> <li>Never touches text you're typing — inputs, textareas and contenteditable regions are left alone.</li> <li>Switching it off restores the page exactly. No reload needed.</li> <li>Regex patterns are tested for catastrophic backtracking before they ever run on a page, with a time budget as a second line of defence.</li> <li>Work is spread across idle time, so large pages don't freeze.</li> <li>Keeps up with pages that load content as you scroll.</li> </ul> <h3>Privacy</h3> <p>No network requests. No analytics, no telemetry, no account, no remote code. Your rules live in local browser storage and go nowhere else.</p> <h3>Interface</h3> <p>A full options page for managing rules, groups, import/export and preferences, plus a popup for quick toggles and adding a rule on the spot. Light and dark themes, and everything works from the keyboard — including reordering rules, so drag isn't the only way.</p> <p><a href="https://github.com/DerMaxiAufGit/Word-Replacer-Extension">Source code on GitHub</a> — MIT licensed.</p> ## Rankings - #124,758 — Overall - #130 — rule - #152 — replace - #196 — replay ## Permissions and access ### Permissions - `storage` - `tabs` - `contextMenus` - `activeTab` ### Host permissions - `` ### Content script matches - `` ## Safety - **Risk impact:** High risk impact - **Risk likelihood:** High risk likelihood ### Analysis details - Grants access to browser tabs, which can be used to track user browsing habits and history, presenting a privacy concern. - This extension has low user count. Unpopular extensions may not be stable or safe. > Some risk analysis details are omitted from this free response. 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