GlassBar vs Sider vs Monica vs Merlin
GlassBar, Sider, Monica, and Merlin are browser extensions that put an AI assistant on the page you’re reading — MaxAI, often shortlisted with them, is included below too. As of July 2026, GlassBar is the only one of the five with an extension on Mozilla Add-ons — including Firefox for Android — and the only one that works without an account, credits, or a subscription: you bring your own API key or run a local model, and pay $15 once if you want saved chats.
The short version
Anyone hunting for the best AI sidebar extension ends up weighing the same five things: what it costs, how credits are limited, whether an account is required, where your text goes, and which browsers it runs in. This AI browser assistant comparison covers exactly those, plus one axis the others rarely mention — local model access.
The structural difference is simple. Sider, Monica, Merlin, and MaxAI are subscription services: your requests route through the vendor’s servers, usage is metered per account, and the subscription buys you bundled access to frontier models without managing keys. GlassBar is a client: it sends the page and your question straight from the browser to the provider you picked, with your own key, and the developer never sees your data. Neither model is wrong — one trades control for convenience, the other trades convenience for control.
Side-by-side, as of July 2026
Competitor details are as of July 2026, drawn from the sources at the end of this page — vendor pricing pages where fetchable, otherwise Mozilla Add-ons listings and third-party pricing trackers. Sider, Monica, and Merlin block automated access to their pricing pages, so treat exact free-tier numbers as approximate. GlassBar details describe v0.4.1.
| Feature | GlassBar | Sider | Monica | Merlin | MaxAI |
|---|---|---|---|---|---|
| Firefox extension | Yes — live on Mozilla Add-ons, Firefox 142+ | No — Chrome and Edge builds only | No — extension supports Chrome and Edge | No listing found on Mozilla Add-ons | No — Chrome and Edge, plus a web app |
| Firefox for Android | Yes — enabled on the same listing | No | No — separate native Android app instead | No — separate native mobile app instead | No |
| Pricing model | Free; Pro is $15 once for Saved Chats | Subscription with credits, $4.20–$16.70/mo (tracked) | Subscription with credits, Pro from ~$8.30/mo billed annually | Subscription, Pro $19/mo with a fair-use cap | Subscription, $12/mo billed yearly or $30/mo monthly |
| Free-tier credit limits | None — no credit system at all | ~30 basic credits/day (sources vary) | Daily credit allowance, resets every 24 h | 102 queries/day on basic models | Unlimited fast-model chat; 3 Pro chats/day |
| Works without an account | Yes — no sign-up, no login | No, per third-party guides | No — credits and history are account-based | No — account unlocks models and sync | No — Free plan begins at “Create account” |
| Bring your own API key | Yes — Anthropic, OpenAI, Gemini, OpenRouter, xAI, Groq, DeepSeek, any OpenAI-compatible endpoint | Partial — OpenAI and OpenAI-compatible keys | None documented | Historical — OpenAI keys only; current support unconfirmed | Reported in 2024; absent from the current pricing page |
| Where your requests go | Browser to your chosen provider, directly — no middle server | Through Sider’s service; credits metered per account | Through Monica’s service, per its privacy policy | Through Merlin’s service; usage capped server-side | Through MaxAI’s service; chats metered per account |
| Local models (Ollama / LM Studio) | Yes — fully offline on localhost | None documented | None documented | None documented | None documented |
| One-time purchase option | Yes — $15 once, free updates | No — subscription only | No — subscription only | No — subscription only | No — subscription only |
When Sider makes sense
Sider is the pick if you live in Chrome or Edge and want one subscription that bundles GPT-5.x, Claude, Gemini, and DeepSeek behind agent-style sidebar features — no API keys to manage. Third-party trackers put paid tiers between $4.20 and $16.70 a month, and it does accept a custom OpenAI or OpenAI-compatible key alongside its own credits. The trade: no Firefox build, an account-metered credit system, and requests that pass through Sider’s service. If Sider is the one you’re actually deciding against, the longer take is at GlassBar as a Sider alternative.
When Monica makes sense
Monica is the pick if you want the same assistant everywhere Monica runs — a Chrome/Edge extension, desktop apps, and native Android and iOS apps — with image and video models bundled in. Its free tier resets a daily credit allowance every 24 hours, and paid plans start around $8.30 a month billed annually per 2026 pricing writeups. The trade: no Firefox extension, no documented bring-your-own-key option, and a privacy policy that says your inputs and uploads are processed through Monica’s service.
When Merlin makes sense
Merlin has the most generous free tier of the four: 102 queries a day on basic models plus unlimited YouTube summaries, per 2026 reviews. Pro at $19 a month bundles GPT-5.2, Claude Opus 4.6, Gemini 3.0, and more — marketed as unlimited, though Merlin’s own feedback board documents a fair-use cap of roughly $100 of usage a month. The trade: no Firefox listing found on Mozilla Add-ons as of July 2026, an account required to unlock models, and older OpenAI-key support whose current status is unconfirmed.
When MaxAI makes sense
MaxAI’s bundled Pro is $12 a month billed yearly, per its own pricing page — plus unlimited chat on a fast free model and a standalone web app at maxai.co. The trade: even the Free plan starts at “Create account,” the free tier allows only 3 Pro chats a day, and there is no Firefox extension and no documented local model support.
When GlassBar makes sense
GlassBar is the pick if you use Firefox — desktop or Android — or if you want an AI sidebar without a subscription and without a company in the middle. There is no account, no backend, no telemetry: your key lives in browser storage and the page text goes directly to whichever provider you chose. It is the only tool in this table with documented local model support — point it at Ollama or LM Studio and nothing leaves your machine. And it is the only one free of credit limits: the free tier is the full product, not a trial, and Pro is $15 once for Saved Chats — persistent per-page conversations, searchable history, Markdown and JSON export.
Be clear about what GlassBar doesn’t do. It bundles no model access — you bring an API key (you pay the provider for usage) or run a local model. On Chromium browsers it works from one codebase, but the Chrome Web Store listing is still pending, so Chrome, Edge, and Brave users sideload the dev build today. And there are no native mobile apps — mobile means Firefox for Android. More detail in the FAQ.
Sources
Competitor claims above are as of July 2026 and trace to these pages:
- Sider — sider.ai/pricing, Mozilla Add-ons search, SaaSworthy pricing tracker, SiliconFlow custom-key doc
- Monica — monica.im/pricing, monica.im/privacy, Mozilla Add-ons search, 2026 pricing writeup
- Merlin — getmerlin.in/pricing, Mozilla Add-ons search, Merlin feedback board (fair-use cap), 2026 pricing article, AppSumo key Q&A
- MaxAI — maxai.co/pricing, Mozilla Add-ons search, 2024 review (BYOK mention)
- GlassBar — Mozilla Add-ons listing, privacy policy
Products and prices change; if a figure above has drifted, the vendor’s own pricing page wins.
Ask AI about the page you're on.
Your key, no account, nothing leaves your browser. Free to use. $15 to remember.