Firefox Browser Add-ons
  • Extensions
  • Themes
    • for Firefox
    • Dictionaries & Language Packs
    • Other Browser Sites
    • Add-ons for Android
Log in
Preview of SpellBolt

SpellBolt by 👾DR.WATT👾

English Spelling/Grammar suggestions on any text field. Running 100% Local and Private. Your data never leaves your device.

ExperimentalExperimental
5 (3 reviews)5 (3 reviews)
5 Users5 Users
You’ll need Firefox to use this extension
Download Firefox and get the extension
Download file

Extension Metadata

About this extension
A lightning-fast spell-checker for modern writers

Spellbolt is a blazing-fast, privacy-first spell-checker built for clarity, performance, and complete control.

It works entirely offline — no cloud syncing, no tracking, no ads — just sharp, real-time spelling corrections as you type.

Crafted for web-native writing, Spellbolt uses a precision-built typo map and a lean, multi-dialect engine to catch real-world errors without ever slowing you down.

From blog posts and emails to documentation and chat, Spellbolt keeps your text clean — without ever touching the internet.

Who it's for:

⚡ Writers, coders, and content creators who value speed and simplicity
🔐 Privacy advocates and professionals in secure environments
🇬🇧🇺🇸🇨🇦🇦🇺 Multinational users needing smart English dialect support
💬 Users frustrated with cloud-based bloatware and upsell fatigue

Key Features:
  • Real-time typo correction powered by an optimized typo→correction engine
  • 100% offline — no data ever leaves your browser
  • Supports American, British, Canadian, and Australian English
  • Great for markdown, documentation, and everyday web writing
  • Based on HarperJS core, extended with custom enhancements
  • No popups, tracking, subscriptions, or creepy AI logs
  • Lightweight, fast-loading, and memory-efficient

Unlike bloated grammar suites or data-harvesting AI tools, Spellbolt stays lean, focused, and local.

Your words, your browser — corrected instantly.
Rated 5 by 3 reviewers
Sign in to rate this extension
There are no ratings yet

Star rating saved

5
3
4
0
3
0
2
0
1
0
Read all 3 reviews
Permissions and dataLearn more

Required permissions:

  • Access browser tabs
  • Access your data for all websites

Optional permissions:

  • Access your data for all websites
More information
Add-on Links
  • Support site
  • Support Email
Version
0.1.9
Size
3.38 MB
Last updated
2 months ago (Jun 10, 2025)
Related Categories
  • Privacy & Security
  • Language Support
License
All Rights Reserved
Privacy Policy
Read the privacy policy for this add-on
Version History
  • See all versions
Tags
  • facebook
  • google
  • privacy
  • reddit
  • search
  • social media
  • twitter
  • whatsapp
  • youtube
Add to collection
Report this add-on
More extensions by 👾DR.WATT👾
  • There are no ratings yet

  • There are no ratings yet

  • There are no ratings yet

  • There are no ratings yet

  • There are no ratings yet

  • There are no ratings yet

Go to Mozilla’s homepage

Add-ons

  • About
  • Firefox Add-ons Blog
  • Extension Workshop
  • Developer Hub
  • Developer Policies
  • Community Blog
  • Forum
  • Report a bug
  • Review Guide

Browsers

  • Desktop
  • Mobile
  • Enterprise

Products

  • Browsers
  • VPN
  • Relay
  • Monitor
  • Pocket
  • Bluesky (@firefox.com)
  • Instagram (Firefox)
  • YouTube (firefoxchannel)
  • Privacy
  • Cookies
  • Legal

Except where otherwise noted, content on this site is licensed under the Creative Commons Attribution Share-Alike License v3.0 or any later version.