5 Chrome extensions riding the AI side-panel wave (week of May 26–Jun 2, 2026)

The five extensions

1. Pretty Prompt — 40K installs, subscription, "Grammarly for AI prompting"

• What it changes in the browser: Injects a one-click "optimize" button into the prompt input boxes of ChatGPT, Claude, and Gemini. The extension rewrites the user's prompt in-place and shows a before/after diff — no copy-paste to a separate tool, no new tab. The AI platform itself never knows the button is there. 1
• Monetization model: Freemium subscription. Free tier covers basic prompt optimization; Pro tier unlocks advanced rewriting modes and context retention across sessions. The team — Ilai Szpiezak and Charlie Day, London-based duo, fully bootstrapped — pivoted to Pretty Prompt from a prior product (Dolphin AI) when users started asking to pay before a paywall existed. 1
• Estimated MRR: Not publicly disclosed. At 40K installs × 2% paid conversion × $8/mo (illustrative mid-tier): ~$6,400/mo. The duo has been featured by Stripe and appeared on Google's Chrome extension podcast, so the actual figure is plausibly higher. Any specific number here would be fabricated.
• Why Chrome specifically: The extension intercepts textarea DOM elements across chatgpt.com, claude.ai, and gemini.google.com in a single package. No web app on a different origin can touch those textareas. A mobile keyboard app could intercept input system-wide but can't read existing prompt content for context scoring.
• Reproduction signal: Ilai's stated lesson: "small products are easier to understand, easier to adopt, often easier to sell." 1 The "Grammarly for X" pattern on any structured input field is the signal. Candidates: SQL quality scorer injected into any web-based DB console, commit message grader in GitHub's commit textarea. Same DOM-injection + scoring API core; three-week build each.

2. Web Clipper for NotebookLM — 25K installs, one-time purchase

• What it changes in the browser: Clips any open browser tab — YouTube video, Google Drive file, PDF, web article — directly into Google's NotebookLM (an AI-powered research notebook) as a source, without leaving the current tab. The extension handles YouTube channel batch-clipping, Drive sync, and PDF upload. All features were added from user requests. 3
• Monetization model: One-time purchase — core features included in a perpetual license with no recurring charge. The developer, Stéphane Turquay (Switzerland, solo), started it as a holiday project to solve his own research workflow friction. 3
• Estimated MRR: Not publicly disclosed. At 25K installs × 1.5% paid conversion × $9.99 one-time (annualized monthly): ~$375/mo in new installs converting. As a one-time purchase, MRR understates the actual value — cohort payback happens at install, then falls to near-zero unless the user buys again. The more relevant metric is cumulative revenue.
• Why Chrome specifically: NotebookLM's web UI doesn't expose a clipping API. The extension reads the current tab's URL, title, and content, then authenticates to the user's NotebookLM session using the same browser cookies — a cross-origin data handoff only possible from inside the extension sandbox.
• Reproduction signal: Turquay's largest user base is Japan and South Korea — markets he never marketed to, who found and spread the extension organically. 3 Tools that reduce friction on an AI platform with an engaged non-English user base don't need English marketing to grow. Any platform with an active Japanese or Korean community (Perplexity, Claude, local LLMs) likely has an unserved clipping layer open.

3. Overline — ~5K installs, freemium, real-time AI captions on any browser video

• What it changes in the browser: Adds real-time AI captions and on-the-fly translation to any tab playing audio or video — YouTube, Netflix, Zoom, local video files in Chrome, anything. Technically, it works at the tab audio capture level rather than via DOM injection: the extension captures the tab's audio stream and pipes it sub-second to a speech API, returning a streaming transcript overlay. No DOM modification of the video player is required. 4
• Monetization model: Freemium — free plan includes 20 minutes of captions/month; paid plans for heavier use (pricing not publicly detailed in the post). Developer handle: u/ma1ms, building alongside a day job. 4
• Estimated MRR: At 5K installs × 5% paid conversion (audio tool users tend to upgrade quickly when they hit caps) × $6/mo (estimated mid-tier): ~$1,500/mo. Conversion rate is unverified; treat this as indicative. The 20-min/month free cap is deliberately tight for anyone watching foreign-language content regularly — a sensible upgrade trigger.
• Why Chrome specifically: The tab audio capture API (chrome.tabCapture / chrome.offscreen) is a Manifest V3 extension primitive — no web app on a different origin can access another tab's audio stream. A mobile app requires routing audio through system accessibility APIs, which is far higher friction.
• Reproduction signal: The tab audio capture pattern works for any real-time audio analysis: meeting sentiment scoring (Zoom tab), live sports commentary translation, lecture transcription with searchable history. The core — tab audio → streaming speech API → overlay — is reusable. The 20-min free cap forces upgrade before a user is deep enough to resent it; a well-calibrated freemium trigger worth copying.

4. PlainMarkdown — 650+ users, freemium, webpage-to-Markdown converter

• What it changes in the browser: Converts any open webpage to clean Markdown — stripping ads, nav menus, and boilerplate — with AI-powered title extraction and formatting cleanup. Advanced paid features include AI Actions (run custom instructions on captured content), Destinations (push directly to Notion, Obsidian, or GitHub), and BYOK (bring-your-own API key for AI features). 5

"It doesn't make me wealthy but I feel rich knowing people have recognized a useful tool which to me means the world." 5

• Monetization model: Freemium — free basic capture; paid tier unlocks AI Actions, Destinations, and BYOK. Petar notes conversion quality improved noticeably after the freemium tier launched: "Continued to double-down on the extension, added a few advanced features (AI Actions, Destinations, BYOK) and enabled a Freemium product." 5
• Estimated MRR: At 650 installs × 3% paid conversion × $7/mo (estimated, no public pricing page found): ~$136/mo. The 650-user base is small but the origin story — freemium conversion improving after paywall launch, not before — is the actual signal here. The extension has room to grow by an order of magnitude without hitting category saturation.
• Why Chrome specifically: The extension reads the active tab's full DOM, runs an AI extraction pipeline, and optionally authenticates to Notion, Obsidian, or GitHub on the user's behalf — three separate origin handoffs in one package. A web scraper does the same DOM access but requires manual URL input. The extension acts as a persistent agent on the user's current page.
• Reproduction signal: BYOK is underused in extensions. By letting power users plug in their own OpenAI or Anthropic key, Petar eliminated marginal AI cost on the highest-usage cohort — the exact users most likely to abuse a fixed-price plan. Any extension with AI features and uncertain usage distribution should evaluate BYOK as a cost control mechanism, not just a feature.

5. Notion Smart Clipper — one-time Pro unlock, auto-fills Notion database fields

• What it changes in the browser: Detects the type of page the user is viewing — article, YouTube video, Amazon listing, recipe, job posting — and auto-extracts structured fields into the correct Notion database properties. The free tier clips pages cleanly. The one-time Pro unlock adds database selection and full field mapping, with no subscription. 7

• Monetization model: Free + one-time Pro unlock ("no subscription" — developer-stated). Pro adds database selection and field mapping. 7
• Estimated MRR: Unverifiable at launch — no install count available. At 500 installs × 10% one-time conversion × $9.99: ~$500 in first-month revenue. One-time pricing on a tool with clear job-to-be-done tends to see higher initial conversion than subscription; the "no subscription" messaging removes the objection that kills most SaaS impulse purchases.
• Why Chrome specifically: The extension reads the active page's DOM to detect content type and extract structured data, then authenticates to the user's Notion workspace using the browser session — a cross-origin DOM read + API write sequence no web app can perform outside the extension sandbox. Notion's own clipper uses the same mechanism; this one just executes it better.
• Reproduction signal: Any SaaS tool with a neglected browser companion is a candidate for this play. The pattern generalizes: Airtable's bookmarklet, Coda's web clipper, Linear's capture tool. The structural advantage of "fixed version of official broken tool" is that search intent already exists — users are Googling "Notion clipper alternative" today. The hard part is keeping up with platform API changes, not acquiring users.

At a glance

What the conversion data actually says

1. Price model should match usage frequency. Shota switched PaletteGrab from $2.99/month to $3.99 one-time and conversion jumped 60%. 8 Notion Smart Clipper has the same profile — occasional, high-intent use fits one-time purchase, not subscription.
2. Checkout leakage is a bigger lever than install growth. ExtensionPay loses 30–40% of upgrade clicks before checkout completes. 8 A 10-point improvement in checkout completion on a 0.8% base rate beats doubling installs.
3. Low star ratings are usually limit friction, not product quality. Most negative CWS reviews come from free users hitting caps. 8 The fix is showing more value before the wall, not lowering it.