An infinite zoomable timeline of everything — from the Big Bang to today.
Zoom from cosmic epochs (13.8 billion years ago) down to individual days, weave events through thematic threads, explore the knowledge graph of how history connects, and — optionally — bring your own AI key for conversational features.
Live at chronosapp.org.
- Infinite zoom — one viewport, from the formation of the universe to this morning's headlines. Events reveal themselves as you zoom.
- Event discovery that doesn't hallucinate — Wikidata's SPARQL graph supplies real, dated events across nine themed categories (science, literature, art, politics, disasters, inventions, sport & culture, revolutions, warfare) with weighted quotas so no single theme dominates.
- Knowledge graph visualization — click any well-documented event and see its causes, effects, sub-events, and siblings as an interactive force-directed graph. Sourced from Wikidata properties (P828, P1542, P361, P155/P156, P585/P580/P577). Relations are labeled specifically ("Part of: Seventh Russo-Turkish War", not "related event").
- Thematic timelines (parallel threads) — overlay multiple themed tracks, see where they converge, and ask the app to validate convergences you hypothesize yourself.
- Today in History — Wikipedia's "On This Day" data, enriched with Wikidata coordinates and categories. Free, no AI required.
- Globe view — click any region × year to see what was happening there.
- Optional AI features — chat with a history guide, generate counterfactuals, chat with historical figures, fact-check events, discover primary sources, compare perspectives, generate quizzes, classroom curricula, and more. All AI calls run directly in your browser against your chosen provider (Anthropic, OpenAI, Google Gemini, or a local Ollama). The Chronos server is never in the AI path — your key and messages never touch our infrastructure.
Every AI request is a direct HTTPS call from the browser tab to the
provider's API. There is no proxy. There is no server-side logging.
Open your devtools Network tab while using any AI feature and you'll
see requests to api.anthropic.com / api.openai.com /
generativelanguage.googleapis.com — never to our domain.
This is enforced by architecture, not policy. The server has no AI
endpoint — there is literally nothing server-side that could receive
or log an API key. You can read the short server/api/index.ts to
confirm.
You configure your key via the in-app Settings panel. It's stored in localStorage and never leaves this browser.
- Node.js 20+
- PostgreSQL 16+ (optional — features degrade gracefully when absent)
git clone https://github.com/ogoldberg/chronos.git
cd chronos
npm install
# Optional: copy the env template if you want auth / persistent caching
cp .env.example .env
npm run devThe dev server runs at http://localhost:5173.
To use AI features: open the app, press ⌘K → "AI settings", and paste your own API key from Anthropic, OpenAI, or Google AI Studio.
No API key is needed to use the timeline itself — Wikipedia + Wikidata power the free tier.
npm run build
npm startServes the static bundle + the free API (Wikipedia/Wikidata proxy, event cache, optional auth) from a single Node process.
┌───────────────────────────────────────────────────────────────┐
│ BROWSER │
│ │
│ ┌──────────────┐ ┌────────────────┐ │
│ │ Chronos UI │────>│ Your AI key │ │
│ │ (Vite+React) │ │ in localStorage│ │
│ └───────┬──────┘ └────────────────┘ │
│ │ │
│ │ AI requests (direct, HTTPS) │
└──────────┼────────────────────────────────────────────────────┘
│
▼
┌────────────────────┐
│ api.anthropic.com │ (or api.openai.com,
│ + provider │ generativelanguage.googleapis.com,
│ │ or your local Ollama)
└────────────────────┘
┌───────────────────────────────────────────────────────────────┐
│ BROWSER ──────> CHRONOS SERVER ──────> Wikipedia / Wikidata │
│ (free data only — no keys, no AI) │
└───────────────────────────────────────────────────────────────┘
Source layout:
src/
├── ai/ # Browser-direct AI provider adapters
│ ├── providers/ # Anthropic, OpenAI, Google, Ollama (lazy-loaded)
│ ├── callAI.ts # Unified callAI() / streamAI() entry point
│ ├── prompts.ts # System prompts for every feature
│ └── types.ts
├── features/ # Feature modules (events, chat, today, graph, ...)
├── canvas/ # Timeline rendering + viewport math
├── stores/ # Zustand stores (timeline, UI, AI config)
├── services/ # Wikipedia/Wikidata/fact-check clients
└── components/ # Shared components (command palette, date picker)
server/
├── api/ # Free endpoints only — no AI routes
│ ├── routes/ # events, discover, today, community, config, ...
│ └── middleware/ # rate limit, validate
├── services/ # onThisDay, wikidataGraph (SPARQL)
└── seed.ts # Dev-only DB warmer (uses env AI key)
- React 19, TypeScript 5, Vite 8
- Zustand (state), Canvas 2D (timeline rendering)
- PostgreSQL + Better Auth (optional)
- Anthropic / OpenAI / Google Generative AI / Ollama SDKs (client-side)
- Wikipedia REST API + Wikidata SPARQL
Contributions welcome. See CONTRIBUTING.md for how to set up your dev environment, the conventions the codebase follows, and how to open a good PR.
Issues, feature requests, and ideas all go in GitHub Issues. Please search before filing.
If you find a vulnerability, please email security@chronosapp.org
instead of opening a public issue. See SECURITY.md for
details.
MIT — free to use, modify, and redistribute.