Zero Browser — Product Requirements Document (PRD)

Version: 0.1 (Draft) Owner: Vedant Nimbarte Last updated: 2026-07-21 Status: Draft for review

1. Summary

Zero is an open-source, privacy-first, AI-native desktop web browser built entirely from scratch in Rust — including its own rendering engine, JavaScript engine, and networking stack. It targets Windows, macOS, and Linux at launch.

Zero's product surface is minimal and spacious (design language inspired by Arc, Dia, and Comet) with vertical tabs as the primary navigation model. Its differentiation rests on four pillars: privacy & data sovereignty, performance & minimalism, AI-native browsing, and India-localization.

Positioning line: "India's own browser — private by default, fast by design, intelligent by nature."

2. Problem statement

Dependence. Nearly every browser Indians use is foreign-owned and Chromium/WebKit-based (Chrome, Edge, Brave, Arc, Comet). There is no sovereign, from-the-ground-up Indian browser.
Privacy erosion. Mainstream browsers monetize attention and data; trackers are pervasive; users have little real control.
Bloat & clutter. Traditional browser chrome is dense and horizontal-tab heavy; tab overload is a daily pain.
AI is bolted on. Where AI exists, it's a sidebar afterthought, not woven into how you navigate and act on the web.
Weak localization. Indian-language UX, local search, and India-specific integrations (UPI, DigiLocker, regional content) are underserved.

3. Vision & strategy

Vision: Every Indian on the web through a browser they can trust — that respects their privacy, runs fast on modest hardware, understands their languages, and helps them get things done with AI.

Strategy: Win a passionate early-adopter base (privacy-conscious users, developers, students, designers) with a beautiful, minimal, AI-native shell — while transparently building out a genuine Rust engine in phases. Use the open-source community as both contributor pool and trust signal.

Moat over time: (a) a sovereign, auditable, Rust-safe engine; (b) India-first localization and integrations that global players deprioritize; (c) an AI layer that is private and on-device-first.

4. Goals & non-goals

4.1 Goals (v1)

Ship a stable, beautiful desktop browser on Windows/macOS/Linux.
Vertical tabs, spaces/profiles, split view, command bar.
Privacy by default: tracker/ad blocking, no non-consensual telemetry, local data.
AI-native: page chat, summarize, agentic actions, smart command bar.
India-localization: multi-language UI, Indian-language search, local integrations.
Own rendering + JS engine handling a defined web subset, with a compat fallback.

4.2 Non-goals (v1)

Full parity with Chromium web compatibility (explicitly a multi-phase journey).
Mobile (Android/iOS) apps — later phase.
Browser extension marketplace at parity with Chrome Web Store (limited API in v1).
Enterprise device-management/MDM tooling.
Ad network or data-monetization business model (contradicts positioning).

5. Target users & personas

Persona	Description	Primary need
Priya, the privacy-conscious professional	28, urban, uses many web apps	Trust, no tracking, clean UX
Arjun, the developer/enthusiast	24, tinkerer, OSS contributor	Rust internals, hackability, speed
Meera, the student	20, budget laptop, studies in Hindi/regional lang	Low RAM, localized UI, AI study help
Rohan, the power multitasker	32, 40+ tabs open daily	Vertical tabs, spaces, split view
Community contributor	Global/Indian OSS dev	Clean architecture, good docs

6. Product pillars & requirements

Pillar A — Privacy & data sovereignty

P-A1 (Must): Built-in tracker + ad blocker on by default (EasyList/EasyPrivacy-class + Indian lists).
P-A2 (Must): No telemetry collected without explicit opt-in; when opted in, anonymized and India-hosted.
P-A3 (Must): All user data (history, bookmarks, passwords, cache) stored locally, encrypted at rest.
P-A4 (Should): Optional encrypted sync with user-held keys; sync servers hostable in India / self-host.
P-A5 (Should): Per-site permission model, fingerprinting resistance, HTTPS-first.
P-A6 (Could): "Data passport" — a plain-language dashboard of exactly what's stored and where.

Pillar B — Performance & minimalism

P-B1 (Must): Cold start ≤ 1.5s; new-tab open ≤ 100ms on reference hardware (see §10).
P-B2 (Must): GPU-accelerated compositing; 60fps UI animations; 120fps where display supports.
P-B3 (Must): Idle RAM per background tab meaningfully below Chromium baseline (target set in Architecture).
P-B4 (Must): Minimal, spacious chrome; hide-able toolbar; content-first layout.
P-B5 (Should): Background tab sleeping/discarding; memory pressure handling.

Pillar C — AI-native browsing

C-1 (Must): AI command bar — natural-language navigation, search, and actions from one input.
C-2 (Must): "Chat with this page" — summarize, ask questions, extract, using current tab context.
C-3 (Should): Cross-tab / space context ("compare these 3 tabs").
C-4 (Should): Agentic actions (fill forms, multi-step tasks) with explicit user confirmation.
C-5 (Must): Privacy-preserving AI: on-device model option; cloud calls are explicit, consented, and India-routable.
C-6 (Could): Writing/coding assist inline in text fields.

Pillar D — India-localization

D-1 (Must): UI localized in English + Hindi at launch; framework for ≥8 more Indian languages.
D-2 (Should): Indian-language search & AI (query and answer in regional languages).
D-3 (Should): Local integrations surface: UPI payment awareness, DigiLocker, government-services quick links.
D-4 (Could): Indian content discovery on new-tab (regional news, opt-in).
D-5 (Must): IME/input support for Indic scripts; correct complex-script text shaping in-engine.

Core browser (table stakes)

T-1: Vertical tabs with drag-reorder, groups, pinning, close/restore.
T-2: Spaces/profiles (separate cookie/storage jars, visual themes).
T-3: Split view (2+ panes side by side; see reference image 1).
T-4: Address/command bar with autocomplete, history, bookmarks.
T-5: New-tab page with quick links, search, top stories (reference image 2).
T-6: Downloads, history, bookmarks managers.
T-7: Find-in-page, zoom, reader mode.
T-8: Session restore, crash recovery.
T-9: Settings/preferences with privacy front-and-center.
T-10: Auto-update (secure, signed).

(Must / Should / Could = MoSCoW prioritization.)

7. Key user flows (v1)

First run: Welcome → choose language → import from existing browser (optional) → privacy defaults explained → done.
Open & navigate: ⌘/Ctrl-T → command bar → type query or URL → AI-assisted suggestions → land on page.
Vertical tab management: New tabs stack vertically in left sidebar → drag to reorder/group → pin → collapse sidebar for full content.
Split view: Right-click tab → "Add Right Split" → two panes; drag divider to resize.
Chat with page: Click AI icon / shortcut → sidebar chat scoped to current tab → summarize or ask.
Spaces: Switch space (bottom-left, reference image 1) → different set of tabs, theme, and profile.
Privacy check: Shield icon in toolbar → see trackers blocked on this site → toggle protections.

8. Competitive landscape

Browser	Engine	Vertical tabs	AI	Privacy stance	Notes
Chrome	Chromium	No (native)	Add-on	Weak	Market leader
Edge	Chromium	Yes	Copilot	Medium	MS ecosystem
Arc	Chromium	Yes	Some	Medium	Design leader
Dia	Chromium	Yes	AI-native	Medium	Arc's AI successor
Comet (Perplexity)	Chromium	Yes	AI-native	Medium	Agentic
Brave	Chromium	Optional	Some	Strong	Privacy + crypto
Zero	Own (Rust)	Yes	AI-native	Strong + sovereign	India-first, from scratch

Zero's unique intersection: the only one that is from-scratch Rust engine + sovereign/India-localized + AI-native + minimal design.

9. Business & GTM (open-source product)

Model: Open-source core (permissive license). Optional paid cloud services (encrypted sync, premium AI compute) fund development — never ads or data sales.
Launch sequencing: Private alpha (contributors) → public beta (early adopters) → 1.0.
Community: Public roadmap, RFC process, contributor guide, Discord/Matrix.
Trust/sovereignty angle: auditable code, India-hosted services, transparency reports.
Distribution: direct download (signed installers), plus Linux repos / package managers.

10. Success metrics

Reference hardware for perf targets: mid-range laptop, 4-core CPU, 8GB RAM, integrated GPU (representative Indian student/professional device).

Metric	v1 target
Cold start	≤ 1.5s
New tab open	≤ 100ms
UI frame rate	60fps sustained
Idle RAM / background tab	< Chromium baseline (exact figure in Architecture §perf-budget)
Crash-free sessions	≥ 99.5%
Tracker requests blocked	≥ 90% of known-tracker requests
Web-subset compatibility	100% of the Phase-defined subset renders correctly
Retention (early adopters)	D7 ≥ 30%, D30 ≥ 15% (beta target)

11. Constraints & assumptions

Small team + open-source contributors; from-scratch engine is the schedule risk.
Rust ecosystem crates may be leveraged (e.g. wgpu, tokio) — "from scratch" means we don't embed a browser engine, not that we rewrite GPU drivers.
AI cloud calls require a provider; on-device model constrained by user hardware.
India-hosting requirements may need cloud region availability planning.

12. Open questions

Product name & brand. "Zero" is a working codename. Final name, logo, domain?
License choice. Apache-2.0 (permissive) vs MPL-2.0 (file-level copyleft, Mozilla-style)?
AI provider(s). Which cloud model for v1? Which on-device model (size/quality trade-off)?
Compat-bridge policy. Do we ship the embedded-engine fallback publicly, or dev-only?
Funding. Bootstrapped, grant (e.g. Indian gov/OSS grants), or backed?
Governance. BDFL, foundation, or company-steered OSS?
Which 8+ Indian languages are prioritized after Hindi?

13. Appendix — reference UI

Reference image 1: Arc-style split view, vertical tabs in left rail, spaces at bottom-left, per-tab context menu (Move Left/Right, Add Split). Zero adopts this layout language.
Reference image 2: Dark, spacious new-tab page — centered search, social quick-launch rail, tiled shortcuts, "Top Stories" with category chips, privacy assurances under the search bar. Zero's new-tab page follows this direction.

Detailed visual spec: 02-UI-UX-SPEC.md.