Best BYOK AI Chrome extensions in 2026
The BYOK (bring your own key) Chrome extensions worth trying in 2026 are ShroomPen, GPT Breeze, Wandpen, HARPA AI, Page Assist and Scramble. ShroomPen, Page Assist and Scramble are free with your own key and also run local models. GPT Breeze is free with your key and sells a $15 one-time license. Wandpen’s BYOK plan is a $19 lifetime purchase. HARPA AI needs a paid plan for your own keys. If you want the answer written into the text field you are working in, ShroomPen, Wandpen and Scramble do that; the others are mostly sidebars.
Published
The comparison
| Extension | Your own key from | Local models | Price with your own key | Where the answer goes |
|---|---|---|---|---|
| ShroomPen | OpenRouter (one-click sign-in or key), OpenAI, Anthropic, Gemini, any OpenAI-compatible API | Ollama, LM Studio, any OpenAI-compatible server on localhost | Free | Into the text field you are using, or copy |
| GPT Breeze | OpenAI, Anthropic, OpenRouter and others | Ollama | Free; $15 one-time license for extra features | Its own panel, from highlighted text and saved shortcuts |
| Wandpen | OpenAI, Anthropic, Google, Straico, OpenRouter | Chrome’s on-device Gemini Nano | $19 lifetime BYOK plan (listed as a limited-time price, normally $49) | Inserted into the page after you review it |
| HARPA AI | OpenAI, Anthropic, Gemini, OpenRouter and others | Ollama | Paid plans from $12 a month billed yearly, or $240 once | Sidebar (Alt+A) |
| Page Assist | OpenAI-compatible APIs | Ollama, LM Studio, Chrome’s Gemini Nano | Free, open source | Sidebar and full-page chat |
| Scramble | OpenAI, Anthropic, Groq, OpenRouter | Ollama, LM Studio | Free, open source | Replaces the text you selected |
Checked against each product’s own website, pricing page or README on 25 and 26 September 2026. Prices change, so check before you buy. ShroomPen is our product; the rest of this page tries to be fair about where others do better.
1. ShroomPen: BYOK that writes into the page
ShroomPen is a free Chrome extension for writing where you already are: Gmail, LinkedIn, a CMS, a support tool, a web form. Next to a focused text field it shows Reply, Rewrite, Fix Grammar and Translate buttons that write the result into that field. Ctrl+Q opens an overlay for longer requests, where you read the draft before inserting it.
- Providers: sign in with OpenRouter in one click (OAuth, no key to copy) or paste a key from OpenRouter, OpenAI, Anthropic or Gemini. Any OpenAI-compatible API works too, and local servers such as Ollama and LM Studio need no key.
- Context: attach the current page, the field, selected text, other tabs you pick (PDF tabs included) or a saved Workspace of notes and instructions, one request at a time.
- Privacy: no ShroomPen account, no ShroomPen server, no extension telemetry. Requests go straight from your browser to your provider. Details: how ShroomPen handles your data.
- Weak spots: closed source, Chrome and Chromium browsers only, no summaries of YouTube videos or other research features, and it is a young product from a solo developer.
Add ShroomPen from the Chrome Web Store
2. GPT Breeze: prompt shortcuts and summaries
GPT Breeze summarizes YouTube videos and articles and lets you save prompts as one-click shortcuts for highlighted text. It takes keys from OpenAI, Anthropic, OpenRouter and others, and runs local models through Ollama. The free plan is unlimited with your own key. A one-time license ($15 at the time of writing) adds custom models, and a $24 yearly plan includes AI usage so you don’t need a key.
Better than ShroomPen for: summarizing videos and articles, and reusable prompt shortcuts.
3. Wandpen: a free on-device tier plus lifetime BYOK
Wandpen is a writing assistant with a free tier that uses Chrome’s on-device Gemini Nano (unlimited, works offline) and 100 GPT-5 nano generations a month. Its Lifetime BYOK plan takes keys from OpenAI, Anthropic, Google, Straico and OpenRouter for a one-time $19, listed as a limited-time price down from $49. A Pro subscription at $10 a month includes cloud models. Results can be inserted into the page, including Google Docs.
Better than ShroomPen for: people with no API key at all, thanks to Gemini Nano. ShroomPen is free with your key and supports Ollama and LM Studio, which Wandpen’s site doesn’t mention. See ShroomPen vs Wandpen.
4. HARPA AI: automation first, BYOK on paid plans
HARPA AI is a large sidebar assistant with web automation, page monitoring and a library of commands. It connects to OpenAI, Anthropic, Gemini, OpenRouter and local Ollama models. According to HARPA’s own guide, using your own keys needs a paid plan; the free demo plan is limited to web-session connections and a small number of commands. Paid plans start at $12 a month billed yearly, or $240 for life.
Better than ShroomPen for: automating browser tasks, monitoring pages and running large command libraries.
5. Page Assist: open-source local chat
Page Assist is a free, MIT-licensed sidebar and full-page chat built mainly for local models: Ollama, LM Studio and Chrome’s Gemini Nano, plus OpenAI-compatible APIs. It runs in Chrome, Edge, Brave and Firefox and keeps its data in browser storage.
Better than ShroomPen for: open source you can audit, Firefox, and a full chat interface for local models. It doesn’t write into page fields. See ShroomPen vs Page Assist.
6. Scramble: open-source rewrites from the right-click menu
Scramble is a small MIT-licensed extension. You select text, right-click, and choose an action like “Fix spelling and grammar” or “Improve writing”, and it replaces the selection. It supports OpenAI, Anthropic, Groq, OpenRouter, Ollama and LM Studio. Its maintainer says it is no longer actively developed.
Better than ShroomPen for: people who want open source and only need quick rewrites of selected text.
What BYOK costs in practice
With your own key you pay the provider’s per-token price and nothing else to the extension (if it is free). Two examples from OpenRouter’s price list on 26 September 2026:
- GPT-4o mini: $0.15 per million input tokens, $0.60 per million output tokens. A reply that reads about 2,000 tokens of context and writes 300 tokens costs about $0.0005, so a thousand replies cost about fifty cents.
- OpenRouter’s free models router (
openrouter/free, ShroomPen’s default after OpenRouter sign-in): $0, limited to 20 requests a minute and 50 a day, or 1,000 a day once you have bought at least 10 credits.
A local model through Ollama or LM Studio costs nothing per request; you pay in hardware and speed instead.
How to choose
- You want AI drafts inside Gmail, LinkedIn or web forms with your own key or a local model: ShroomPen.
- You have no API key and want something free right now: Wandpen’s Gemini Nano tier, or OpenRouter’s free models with ShroomPen.
- You want summaries and saved prompt shortcuts: GPT Breeze.
- You want browser automation and don’t mind a subscription: HARPA AI.
- You want open source and local chat: Page Assist.
Related
Questions
What is a BYOK Chrome extension?
BYOK means bring your own key. Instead of paying the extension a subscription for AI, you paste an API key from a provider such as OpenAI, Anthropic, Google Gemini or OpenRouter, and the provider bills you for what you use. Many BYOK extensions also accept a local model server such as Ollama, which needs no key at all.
Is BYOK cheaper than a subscription?
For most people, yes. On OpenRouter, GPT-4o mini costs $0.15 per million input tokens and $0.60 per million output tokens, so a reply with about 2,000 tokens of context and 300 tokens of output costs about $0.0005. Heavy use of large models can still add up, so set a spending limit with your provider.
Is it safe to paste my API key into an extension?
It depends on the extension. Check where it stores the key and where requests go. ShroomPen keeps keys in Chrome’s local extension storage and sends each key only to its own provider, with no ShroomPen server in between. Use a key with a spending limit, and revoke it at the provider if you stop using the extension.
Which BYOK extensions work with Ollama?
ShroomPen, Page Assist, Scramble and GPT Breeze all list Ollama support, and HARPA AI has an Ollama guide. Chrome extensions usually need Ollama’s OLLAMA_ORIGINS variable set to allow them; Page Assist handles it for localhost itself.
Can I use a BYOK extension for free?
Yes. The extension can be free (ShroomPen, Page Assist, Scramble, GPT Breeze’s free plan), and so can the model: a local model through Ollama or LM Studio costs nothing, and OpenRouter has free models, rate-limited to 50 requests a day until you have bought at least 10 credits.