AI Chrome extension pricing compared (2026)
A plain reference table of what every major AI Chrome extension charges, what the free tier really gives you, and what it works out to per message. No affiliate links, no rankings bought by vendors.
The full table
| Extension | Free tier | Entry paid | Mid tier | Model | Reads page? |
|---|---|---|---|---|---|
| WriterPi | 10 no signup / 25 mo | $1 (3-day pack) | $6/mo · 500 msgs | Message cap | Yes |
| Sider | Daily cap | ~$8-10/mo | ~$20/mo | Subscription | Yes |
| Monica | Demo-level | ~$10/mo | ~$20/mo | Subscription | Yes |
| Merlin | Limited credits | Credit packs | Scales fast | Credits | Partial |
| Grammarly | Real free tier | ~$12/mo | ~$15-30/mo | Subscription | Your text only |
| ChatGPT for Google | Free | — | — | Uses your login | No |
| Compose AI | Limited | ~$10/mo | ~$30/mo | Subscription | Partial |
| Wiseone | Limited | ~$10/mo | — | Subscription | Yes |
| HARPA AI | Limited | ~$8/mo | ~$20+/mo | Subscription | Yes |
| MaxAI | Limited | ~$10/mo | ~$20/mo | Subscription | Yes |
Cost per message — the number that actually matters
Headline monthly price tells you very little. What matters is what a single useful message costs you. Rough maths on the mid tiers:
| Tool | Monthly | Messages | Approx cost / message |
|---|---|---|---|
| WriterPi Pro | $6 | 500 | ~$0.012 |
| WriterPi Max | $9 | 800 | ~$0.011 |
| Sider mid | ~$10 | varies | ~$0.02-0.05 |
| Monica mid | ~$10 | varies | ~$0.02-0.05 |
| ChatGPT Plus | ~$20 | very high | Low if used daily, terrible if not |
Competitor message allowances aren't always published clearly, which is itself informative. Where a vendor doesn't state a cap, assume there is one.
Three pricing traps to watch for
1. "Unlimited" that isn't
Several extensions advertise unlimited usage and then apply an undisclosed fair-use throttle. If the pricing page says unlimited but the FAQ mentions "reasonable use", there's a cap — you just don't get to know what it is until you hit it.
2. Annual-only discounts
A tool showing "$8/month" often means $96 billed annually, with the real monthly price being $15. Check whether the number you're seeing is the monthly or annual-equivalent rate.
3. Credit systems that reprice quietly
With credit-based tools, the vendor can change how many credits an action costs without changing the advertised price. Your effective cost goes up and the pricing page still says the same number.
What actually drives these prices
Every one of these tools pays per-token costs to an underlying AI provider. That's the floor. On top of that sits infrastructure, payment processing (2-3%), support, and margin.
Which is why the $1 three-day pack is unusual — it's priced close to cost, deliberately, to let people test properly before committing. Most vendors won't do this because short packs don't produce predictable recurring revenue.
How to pick without overpaying
- Estimate your real usage. Count how many times you'd genuinely use AI in a week. Multiply by 4. Most people overestimate by 3x.
- Start on a free tier for two weeks. You'll learn your actual number.
- Buy the smallest tier that covers it. You can always upgrade; downgrading mid-cycle usually isn't refunded.
- Set a calendar reminder before renewal. The single biggest AI cost for most people is subscriptions they forgot to cancel.