Browser/ebook extension that blocks triggering words
Problem
A reader with OCD asks for an app that can block out specific words across the internet and ebooks, because intrusive trigger words are ruining their ability to read. Existing content filters are built for parents/kids (whole-site blocking), not for adults who need granular per-word masking in everyday reading.
Opportunity
A browser extension + ebook reader integration that detects and visually masks user-defined words in real time, aimed at OCD/anxiety/trauma-trigger management — a niche but deeply undeserved accessibility tool with clear willingness to pay.
Market analysis
The core browser use case is already solved well by free tools like Advanced Profanity Filter, which supports custom word lists with censor/substitute/hide modes — it's just framed for profanity, not therapeutic use. The real gap is ebooks, where DRM and closed reader ecosystems make per-word masking genuinely hard.
Market · Adults with OCD, anxiety, or trauma triggers who need granular word masking; niche but high-need and largely invisible to filter vendors.
Pricing · Free extensions dominate the browser side; willingness to pay exists for a polished, therapy-adjacent product (one-time $10-30 or $2-5/month is plausible for ebook coverage).
Pros
- + Real, visceral need from users who currently can't read comfortably.
- + Browser MVP is cheap to build and technically proven.
- + Reframing from profanity filtering to accessibility/trigger management is genuinely unclaimed.
Cons
- − Advanced Profanity Filter is free and covers most of the browser case today.
- − Ebook side is blocked by DRM and Kindle's closed ecosystem.
- − Mental-health positioning demands careful, sensitive design and support.
Existing / similar tools
Source
r/Doesthisexist (Reddit)
The non-obvious work here isn’t string matching — it’s matching well. Naive substring filtering breaks on plurals, conjugations, and words embedded in other words, and over-blocking is its own kind of ruin for a reader with intrusive thoughts. Ebook coverage is the actual moat: sideloading via Calibre can filter EPUBs today, but meeting users inside Kindle or the Kindle app is where the willingness to pay lives, and it’s exactly where platform gates are highest. A realistic wedge is owning the therapeutic framing — curated trigger-list management, gradual exposure settings — that a generic profanity filter will never build.