ChatGPT in any tab: GPT models in a browser sidebar

The sidebar is a chat that can see the tab you are on. Choose a GPT model and the answer comes from GPT; change your mind and pick another model without losing the conversation.

Questions about the page you have open

Ask it to summarise an article, explain a table, draft a reply to the email you have open, or answer a question about the page. You do not copy and paste into a separate tab, which is the main reason to use a sidebar at all. The same works on YouTube: see YouTube summaries.

Editing text where it already lives

Select text on any page and rewrite it in place with a tone and length picker, a word-level diff against the original, and undo. It works in Gmail, Google Docs, LinkedIn or any text box.

Files, search and translation

Web search returns cited sources, chat with PDF handles PDF, Word, Excel and CSV files, and page translation shows a page bilingually. It is the same product on the web at app.copilotly.com and in the iOS and Android apps, and the mobile apps work on the free plan.

Yes. as of November 2026, OpenAI's documentation describes a ChatGPT extension installed from the Chrome Web Store. It works with Chrome, Edge, Brave, Opera and Vivaldi. Side chat, which opens beside the page you are viewing, is available in Chrome, Edge, Brave and Vivaldi but not in Opera. OpenAI says it lets you mention open tabs, bring highlighted text into a chat, and asks before using each new website. Check OpenAI's page for what it does on your plan today, because it changes.

When OpenAI's own app is the better choice

If you only use GPT, want OpenAI's features the moment they ship, or want your history to live in your OpenAI account, use OpenAI's app and extension. The browser actions in OpenAI's extension are driven from its desktop app, which Copilotly does not have and does not try to replace. See OpenAI's ChatGPT page for its plans.

Where Copilotly differs

• Every model in one sidebar. GPT, Claude, Gemini, Grok, DeepSeek and Mistral share one menu, so you can compare answers to the same question.
• Side chat in Opera and Firefox. OpenAI lists side chat for four browsers and says Opera lacks it; Copilotly's sidebar runs in Opera and Firefox too.
• Bring your own key. Use your own OpenAI API key and pay OpenAI directly.
• Rewrite, translate and summarise in place on the page you are on.

Be careful with clones: several extensions with ChatGPT in the name are made by unrelated publishers. Check the publisher on the store listing before you install anything. If you are weighing Copilotly against OpenAI directly, the Copilotly vs ChatGPT comparison goes through it in more detail.

OpenAI's model page lists four GPT-6 family models, all with a 1.05M-token context window and text and image input (as of November 2026). The tier decides your Copilotly limit.

Model	Tier	Free plan	Pro plan
GPT-6 Luna	fast	Included, within your token allowance	Included, within your token allowance
GPT-6.1 Terra	premium	10 messages a day, then GPT-6 Luna	Unlimited
GPT-6.1 Sol	premium	10 messages a day, then GPT-6 Luna	Unlimited
GPT-6 Astra	frontier	Your own API key only	30 a day, then GPT-6.1 Sol

GPT-6.1 Terra

OpenAI calls it a fast, efficient model for visual reasoning, precise computer use, and clear, natural writing. It is the recommended default in Copilotly.

GPT-6.1 Sol

OpenAI's description is near-Astra performance for complex work at a lower cost, a balance of intelligence and price. It is the step up when Terra's answer is not careful enough.

GPT-6 Astra

OpenAI's most capable model, for the most demanding work, and the one OpenAI names for complex reasoning and coding. In Copilotly it is frontier: Pro gets 30 a day, then it steps down to GPT-6.1 Sol. On Free it is available only with your own API key.

GPT-6 Luna

OpenAI's most efficient model for focused, high-volume tasks. In Copilotly it is the fast model and the one your chat falls back to on Free once the 10 daily premium messages are used.

Pro is $6.99/week, $19.99/month or $149.99/year, with a 7-day free trial for first-time subscribers. Full limits are on the pricing page and the free plan page.

On the free plan

Yes. The free plan includes GPT-6 Luna and 10 premium-model messages a day, so you can try GPT-6.1 Terra or Sol on real work before deciding anything. A free account is required; a card is not. When the premium messages run out the chat continues on GPT-6 Luna instead of stopping, and the count resets daily.

On your own OpenAI API key

Every model on this page can also run on your own API key. Requests made on your own key are never metered by Copilotly, whatever the model's tier, and that includes frontier models on the free plan, which are otherwise Pro-only. You pay the provider directly at their API rates. The steps are on the bring your own key page.

That is the way to use GPT-6 Astra without Pro. If you already have an OpenAI API account, connect the key and use GPT in the sidebar without paying Copilotly for those messages. You pay OpenAI's API rates, listed on OpenAI's pricing page, which can be more or less than a subscription depending on how much you use it.

Everyday questions and writing

Start with GPT-6.1 Terra. OpenAI positions it for clear, natural writing and for visual reasoning, so it is a reasonable first choice for drafting a reply, explaining a chart on the page, or tidying a paragraph.

When the answer has to be right

Move to GPT-6.1 Sol for a question that needs more careful reasoning, such as comparing contract terms or checking a multi-step calculation. Keep GPT-6 Astra for the genuinely hard problems on Pro, because each one uses one of your 30 daily frontier messages.

Quick lookups and small edits

Use GPT-6 Luna when speed matters more than depth: a definition, a one-line rewrite, a quick translation of a sentence.

Get a second opinion

If an answer matters, ask another model. A GPT answer and a Claude answer to the same question often differ in wording and sometimes in substance, and seeing both is cheaper than finding the mistake later. Neither is right every time. For work you will send or publish, read the result first. The ChatGPT vs Claude vs Gemini guide compares the three on professional tasks, and the guide to AI copilots by profession shows where each tool tends to help.

Context window and image input are the two specifications most people ask about. Here is where one flagship from each provider stands, using each vendor's own documentation where we could read it.

Model	Context window	Image input	Source (Nov 2026)
GPT-6.1 Terra	1.05M	Yes	OpenAI docs
Claude Sonnet 5.5	1M	Yes	Copilotly catalogue
Gemini 4 Argon	1M	Yes, plus audio, video and PDF	Google AI Studio docs
DeepSeek V4 Pro	1M	No (Flash: yes)	DeepSeek docs
Grok 4.7	500K	Yes	xAI docs
Mistral Large 4	1M	Multimodal	Mistral docs

What the table does and does not tell you

A bigger context window means more text fits in one request. It does not mean the model uses all of it equally well, and the rows above say nothing about accuracy, writing style or how careful the reasoning is. The only reliable test is your own task: run it on two models and read both answers.

Price is a separate question

On Copilotly's plans the tier, not the per-token price, sets your limit: ten premium messages a day on Free, unlimited on Pro. Per-token prices only matter if you use your own API key, in which case OpenAI's pricing page is the source.

Give it the page, not a paraphrase

The sidebar reads the tab you have open, so ask about the page directly: "Which of these three options costs least over two years?" works better than retyping the options. If the answer needs numbers from a table, say which table.

Use web search for anything recent

GPT answers from its training unless you turn on web search. For prices, news or anything that changes, search first and open the cited sources.

Pick the model for the job, then escalate

Begin on Terra. If the answer is shallow, repeat the question on Sol rather than rewording it five times. Save Astra for work where an error would cost you.

Set your voice once

Copilotly's memory and custom instructions and My Voice let GPT write closer to your own style, so you edit less. Review what it remembers from time to time.

With Copilotly, yes for all but Safari. ChatGPT in Firefox comes from the Firefox Add-ons listing, and ChatGPT in Opera from the Chrome Web Store build that Opera and Brave install.

Where	Status	How
Chrome	Supported	Chrome Web Store
Edge	Supported	Its own Edge Add-ons listing
Firefox	Supported	Its own Firefox Add-ons listing
Brave	Supported	Installs the Chrome Web Store build
Opera	Supported	Installs the Chrome Web Store build
Arc, Vivaldi	Supported	Install the Chrome Web Store build
Safari	Not yet	There is no Safari build in the App Store
iPhone, Android	Supported	The Copilotly iOS and Android apps, which work on the free plan

On an iPhone or Android phone, use the Copilotly mobile app instead of a browser extension.