Sider AI vs AI Reply Writer: a multi-model sidebar or a reply button?
Sider AI and AI Reply Writer compared: a sidebar with many AI models for chat, PDFs, videos and translation, versus an AI reply button in each app's reply box.
Sider is an AI sidebar for the browser: chat with several AI models side by side, summarise pages, PDFs and YouTube videos, translate and write. AI Reply Writer is a reply tool: a button inside the reply box on 23 sites that reads the conversation and writes the answer in place. Choose Sider for research, reading and comparing models; choose AI Reply Writer for answering messages without leaving the app.
At a glance
| Sider | AI Reply Writer | |
|---|---|---|
| What it is | An AI sidebar with access to several AI models | An AI reply writer: a ✦ AI Reply button inside the reply box |
| Where it works | Any web page, in a sidebar | 23 sites, including Gmail, Outlook, LinkedIn, WhatsApp Web, Instagram, Facebook, Slack and Teams |
| Reads the conversation | Can read the page, PDFs and videos you open | Yes — the thread you have open, plus photos and PDFs in Gmail, Outlook and WhatsApp Web |
| Review replies | Not a focus of the product | Yes — Google Business Profile and Trustpilot, reading the star rating |
| Free plan | Yes, with usage limits | 20 replies a month |
| Paid plans | Paid plans — see their pricing page | Starter $7, Elite $14, Ultra $29 a month |
| Browsers and phone | Browser extensions | Chrome, Edge, Brave, Opera, Vivaldi and Firefox; a web app on phones |
| Sends anything for you? | No — you copy or insert the text | Never — it fills the box, you press Send |
What Sider is
Sider adds an AI panel to the side of the browser. From it you can chat with a choice of AI models — even several at once to compare their answers — summarise the page you are on, chat with a PDF, get the gist of a YouTube video, translate, and draft text. It is a popular all-in-one AI companion for reading and research.
What AI Reply Writer is
AI Reply Writer is narrower. It puts a ✦ AI Reply button in the reply box of each supported app, reads that conversation — the email thread, the chat, the comment and its post, the review and its stars — and writes the reply right there.
- No sidebar, no copying: the draft lands in the box you were about to type in.
- Built per app across 23 sites, so a group-chat reply goes to the right person.
- For businesses: review replies and saved business facts that replies quote.
The main differences
Reading vs replying
A sidebar shines when you are consuming information — long pages, papers, videos. A reply button shines when you are producing many short answers in many apps.
Model choice
Sider's side-by-side model comparison is a real strength for people who care which model answers. AI Reply Writer also offers a choice of models, picked once in settings rather than per question.
Using both
They complement each other: Sider for research, AI Reply Writer for replies.
Pricing
Sider has a free plan and paid plans; its current prices are on its website.
AI Reply Writer has a free plan with 20 replies a month, no card needed. Paid plans are Starter ($7 a month), Elite ($14) and Ultra ($29); higher plans unlock more advanced AI models and larger allowances, and teams can buy the same plans per member. See pricing.
Which should you choose?
- Choose Sider for an all-purpose AI sidebar for reading, research, translation and model comparison.
- Choose AI Reply Writer for writing replies inside Gmail, Outlook, LinkedIn, WhatsApp Web, Instagram, Slack and more.
About this comparison: it is based on each product's public information as of October 2026, and both products change often — check the other product's own website for its current features and prices before you decide. Product names are trademarks of their owners; AI Reply Writer is not affiliated with them.
Frequently asked questions
What is the difference between Sider and AI Reply Writer?
Sider is an AI sidebar for chat, summaries and research with several models. AI Reply Writer is a reply tool built into the reply box of many apps.
Is there a Sider alternative for replying to messages?
AI Reply Writer writes replies in place on Gmail, Outlook, LinkedIn, WhatsApp Web, Instagram, Facebook, Slack and more, with a free plan.
Can AI Reply Writer summarise a page?
Its toolbar panel can summarise the page you are on, but its main job is replies.
Can I use Sider and AI Reply Writer together?
Yes. They work side by side without conflict.
