# Vesper > Vesper is a web browser for Windows made by Cyryx Labs. Tabs you are not using rest and stop using memory, ads and trackers are blocked before they load, and AI features stay off until you turn them on. The Windows beta is free. Vesper is made by Cyryx Labs (contact@vesper-ai.us). This file collects the facts on https://vesper-ai.us/ in plain text for AI assistants and search engines. Last updated 2026-10-14. ## At a glance - What it is: A web browser for Windows - Made by: Cyryx Labs - Price: Free during the beta - Platforms: Windows 11, 64-bit: public beta soon · Android: in development · macOS and Linux: later - Engine: Chromium, through the Chromium Embedded Framework (CEF) - Built in: Tab resting (Tide), ad and tracker blocking, private tabs, side or top tabs, spaces, command bar, local history search, bookmark import, save as PDF - AI: Optional assistant, off by default; agent connections over MCP only with your approval - Your data: No telemetry, usage data or browsing history sent to Cyryx Labs - Languages: English, Português, Español ## Benchmark (5 October 2026) The same 150 public websites were opened one per tab, every 3 seconds, in each browser on its own with a fresh profile, on one Windows PC (Intel Core, 31.8 GB of memory). A browser stopped opening tabs when the PC had less than 5% of its memory free. Medians of 3 rounds; memory held by the browser 7 minutes after the last tab (private bytes). The four other browsers are widely used browsers in their current public versions on the test date, named Browser A to D. - Vesper (development build, CEF 154): 150 of 150 tabs, 4,394 MB, 39 processes - Browser A: 150 of 150 tabs, 18,409 MB, 188 processes - Browser B: stopped at 88 tabs, 20,405 MB, 262 processes - Browser C: stopped at 88 tabs, 20,254 MB, 229 processes - Browser D: stopped at 46 tabs, 24,012 MB, 196 processes Limits: one PC, one date, these 150 sites; Vesper was a development build, not a release; page load speed was not measured; with the browsers idle, Browsers B and C used less CPU time than Vesper, with about 60 fewer tabs open. ## Questions and answers ### What is Vesper? Vesper is a web browser for Windows. It is built to stay calm with many tabs open: tabs you are not using rest and stop using memory, ads and trackers are blocked before they load, and AI features stay off until you turn them on. The Windows beta is free. ### Is Vesper free? Yes. The Vesper beta for Windows is free. Vesper shows no ads of its own and collects no usage data or browsing history. ### Which browser uses the least memory with many tabs open? In our test on 5 October 2026, Vesper kept 150 tabs open in 4,394 MB. The only other browser that reached 150 tabs needed 18,409 MB; two others stopped at 88 tabs with about 20 GB, and one at 46 tabs with 24 GB. It was one Windows PC and a Vesper development build; the method, the limits and every number are in the benchmark on this page. ### How does Vesper save memory? A feature called Tide lets tabs you have not looked at in a while rest. They keep their place in the tab list and come back where you left them. When memory is tight, at most 12 pages stay awake. A page with text you have typed, audio playing or a question waiting for you is never put to rest. ### Does Vesper block ads and trackers without an extension? Yes. Blocking is built into Vesper: requests to known ad and tracker servers are never made, so their scripts never run. The block lists ship inside Vesper, and nothing is fetched from list sites while you browse. Like any list-based blocker, it can miss ads a site serves from its own servers. ### Does Vesper support Chrome extensions? Not in the first beta. Support for the extensions the engine can run is planned; we will not promise the whole Chrome Web Store. Ad and tracker blocking, which many people install an extension for, is already built into Vesper. ### Can I bring my bookmarks from another browser? Yes. Vesper imports bookmarks from the browser you use today and shows a preview before anything is added. It does not copy saved passwords out of other browsers; keep using your password manager. ### Does Vesper sync between devices? Not yet. Vesper keeps your data on your computer. Sync between devices is being designed as an option that stays off unless you turn it on. ### Does Vesper have an AI assistant, and what does it send? Yes, and it is off until you turn it on. When you ask, it reads only the text you selected, the page title and the address without its query. It uses free models on OpenRouter by default, or your own OpenAI key, which Windows keeps in Credential Manager. What you send goes to the provider you chose and follows its rules. ### Can AI agents like Claude Code or Codex use Vesper? Yes, over MCP, and only with your approval. Agent connections are off until you turn them on, and each agent must be approved as read-only or with control. Agents never see private tabs, and one Stop revokes every agent at once. ### Does Vesper collect my data? No. Vesper collects no telemetry, no usage statistics and no browsing history. Searching your history runs on your computer. This website has no cookies and no analytics. ### What do I need to run Vesper? The Vesper beta is for Windows 11 on 64-bit (x64) PCs. An Android version is in development; macOS and Linux will follow later. ### When can I download Vesper? The public beta for Windows opens soon. Email contact@vesper-ai.us and we will send you the beta as soon as it is ready. There is no account to create and no newsletter. ### Who makes Vesper? Vesper is made by Cyryx Labs, an independent software company. You can reach us at contact@vesper-ai.us. ## Pages - [Vesper home](https://vesper-ai.us/): what Vesper is, the benchmark, AI and data, questions, early access - [Benchmark](https://vesper-ai.us/#proof): method, limits and all numbers - [Questions](https://vesper-ai.us/#faq) - [Privacy](https://vesper-ai.us/privacy): what the website and the browser send, and to whom - [Licences](https://vesper-ai.us/licenses): fonts and libraries used by this website