# Show HN: Browserr – An MCP-first browser for AI agents (one Rust binary)

> Source: <https://browserr.dev>
> Published: 2026-11-14 03:22:22+00:00

Scope

01 / 05
## Everything an agent needs.

Built agent-first: extraction over pixels, stable refs over coordinates, failures you can catch instead of hangs. Three commitments shape the whole engine: it blocks when unsure, it hands the page to a human when a human is needed, and it leaves evidence for everything it did.

| Command | Covers | 
|---|---|
| read | **Structured page reads.** Prose via read_page(), or read_structure(): every element with its rect and selector; fields carry label, constraints, state and validity. | 
| act | **Selector interaction.** click_element() and set_value() — real pointer events, React/Vue-safe writes. | 
| wait | **SPA-aware timing.** Wait for selectors and readiness — no sleeps, no flaky scripts. | 
| observe | **Console capture.** Page messages and network errors arrive as events. | 
| files | **Downloads.** Fetched straight to disk, without page cookies. | 
| survive | **Fast failure, not hangs.** A dead engine surfaces instantly; ephemeral profiles give every run a clean slate. | 
| block | **Adblock built in.** EasyList-based, refreshed weekly. | 
| gpu | **Rendering.** CPU by default — starts anywhere; --gpu opts into hardware. Screenshots on demand, per tab. | 
| compat | **SPA-ready.** React 18 and Vue 3 render and react; IntersectionObserver, IndexedDB, Web Animations, WebGL and WebGL2 (via ANGLE, no GPU needed), clipboard, DecompressionStream; requestIdleCallback and crypto.subtle digests via built-in shims where Servo omits them. | 
| secure | **Token-gated attach.** Unauthenticated sockets get nothing — not even events. | 
| intercept | **Fail-closed interception.** Requests held for an allow / deny / respond decision; unanswered means denied after 5 s. | 
| auth | **Challenges surfaced, not swallowed.** Auth and file-picker events; missing credentials fail closed. | 
| evidence | **Net evidence.** Every fetch/XHR recorded in a ring buffer, in every frame. | 
| frames | **Frame tree.** List frames and walk same-origin ones; cross-origin frames report their url only. | 
| fill | **Form filling.** A whole form in one round trip, with type-aware writes. | 
| submit | **Submit and read the outcome.** Runs the page's validation, then reports url, alerts and invalid fields. | 
| point | **Shared references.** Stable refs and numbered screenshot boxes: the agent says "click 7" and the human knows which one that is. | 
| proxy | **Upstream proxy routing.** browser_start(proxy=...) routes all http/https traffic through a CONNECT tunnel (basic auth in the URL, per-engine rotation); document_status reports the main document's real HTTP status so a block serving a fake 404 is distinguishable from a dead page. | 
| handoff | **Humans take over in a real native window.** Start MCP with headed:true; direct mouse and keyboard input keep working while agent mutations are paused. CAPTCHA support still depends on Servo compatibility. | 
| trust | **Fail-closed by design.** Persistent profiles, evidence shots, an append-only action log, a credential store and a confirm gate on payment submits. | 

Protocol

02 / 05
## The entire protocol, in full.

JSON over loopback. One client, no hidden state — the opposite of CDP's 1000+ endpoints. Events:

- Commands
- 22
- MCP tools
- 42
- Binary
- ~120 MB
- CDP endpoints
- 0
- Dependencies
- 0

SDK

03 / 05
## Three ways in.

Same engine underneath; pick the integration you already have.

| Surface | Covers | 
|---|---|
| mcp | **Model Context Protocol server** with 42 tools, stdlib only. Any MCP-capable agent — Claude, Kai, your own — drives Browserr with zero integration code. | 
| python | **driver.py wraps the raw protocol:** navigation, extraction, form filling, screenshots. No dependencies. | 
| raw | **Anything that can write JSON lines to a socket.** Bindings in any language are an afternoon. | 

Position

04 / 05
## Where it sits in 2026.

Chromium wrappers are the default; alternative engines are the bet. Browserr's edge is the local, trust-first, human-in-the-loop.

|  | Browserr | Lightpanda | Obscura | Chromium headless | 
|---|---|---|---|---|
| engine | **Servo** | own (Zig) | own (Rust) | Blink | 
| js engine | **SpiderMonkey** | own | own | V8 | 
| mcp-native | **yes, 42 tools** | no | partial | via wrappers | 
| protocol size | **22 commands** | CDP-compatible | own + CDP | 1000+ endpoints | 
| footprint | **one ~120 MB binary** | ~16× less than Chromium | ~30 MB | ~200 MB+ | 
| web compat | **Servo 0.8 (text, docs, forms, SPAs)** | growing | growing | full | 
| human handoff | **native window, pause, wait_for_user** | headless only | headless only | via wrappers | 
| trust layer | **evidence, action log, confirm gate** | no | no | no | 
| network policy | **fail-closed, held to a decision** | CDP opt-in | CDP opt-in | CDP opt-in | 

Install

05 / 05
## Get Browserr in seconds.

One package per platform: the engine binary, Python SDK, and the MCP server.

#### Windows x64

Download the zip, unpack anywhere, and point your agent at the MCP server. CPU rendering works out of the box; pass --gpu for hardware rendering.

[↓ Download for Windows](https://github.com/Omodaka9375/browserr/releases/latest)

#### Linux x64 / ARM64

Download the tarball, unpack anywhere, and point your agent at the MCP server. Works headless without a GPU; ARM64 covers the Raspberry Pi 4/5.

#### macOS (Apple Silicon)

Download the tarball, unpack anywhere, and point your agent at the MCP server. Works headless out of the box.

[↓ Download for macOS](https://github.com/Omodaka9375/browserr/releases/latest)

Start

## Start driving the web with your agents.

Free, open source, no account, no telemetry. Runs on every machine.