# Fathom Charts

> Footprint, big trades, imbalances, VWAP… 10 order flow indicators on futures, computed server-side with your parameters. Real time over WebSocket, historical over REST.

Fathom Charts is an API: a WebSocket stream (`wss://stream.fathomcharts.com/v1`) that sends indicator updates in real time, and a REST API (`https://api.fathomcharts.com`) that computes the same indicator, with the same parameters, over a past period. Both return the same objects, identified by a stable `id` and positioned by a `cursor`.

- Authenticate with `Authorization: Bearer <API key>` (`fc_test_…` keys are free and delayed by 10 minutes, `fc_live_…` keys carry the account's offers). The key stays server-side: browsers use short-lived stream tokens.
- Prices are in ticks (multiply by the instrument's tick size, `tickSizeNanos` × 1e-9, to get points); trade prices are whole ticks, computed prices (VWAP, midpoints) can be fractional. Times are nanoseconds since the Unix epoch, sent as strings.
- The TypeScript SDK `@fathom-charts/sdk` (Node 22+ and browsers) handles the stream, resuming and history pagination.
- Every page below is Markdown. Append `.md` to any documentation URL, or send `Accept: text/markdown`, to get the Markdown version of a page. The whole English documentation is a single file at https://fathomcharts.com/llms-full.txt.

## Docs

- [Documentation](https://fathomcharts.com/en/docs.md): Fathom Charts API documentation: order flow indicators computed server-side on futures, streamed in real time over WebSocket or queried over history with REST.
- [Quickstart](https://fathomcharts.com/en/docs/quickstart.md): From API key to your first large order received in real time, then the same request over history.
- [Authentication](https://fathomcharts.com/en/docs/authentication.md): Fathom Charts API keys: test and live keys, scopes and restrictions, rotation and revocation, stream access from a browser.
- [Use with an LLM](https://fathomcharts.com/en/docs/llm.md): Give your AI assistant or coding agent the Fathom Charts documentation as Markdown: llms.txt, Markdown pages and instructions ready to paste.
- [Real time (WebSocket)](https://fathomcharts.com/en/docs/websocket.md): Receive Fathom Charts indicators in real time: connecting, subscribing, initial state, cursors and resuming after a disconnect, stream status and reconnection.
- [History](https://fathomcharts.com/en/docs/history.md): Compute a Fathom Charts indicator over a past range: queries, pagination, cost estimates, and a seamless handoff to the real-time stream.
- [Exports](https://fathomcharts.com/en/docs/exports.md): Export a Fathom Charts indicator over a long range: one compressed NDJSON file, streamed as it is computed and resumable after a disconnect.
- [Limits](https://fathomcharts.com/en/docs/limits.md): Limits of each Fathom Charts plan (connections, subscriptions, history, compute budget, exports), technical limits of the API, and how to track your usage.
- [Plans and billing](https://fathomcharts.com/en/docs/billing.md): Fathom Charts plans: free Sandbox, Live (monthly subscription, real time) and Historical (one-time purchase, lifetime access). Payment through Stripe or Creem depending on your country, activation, cancellation and no refunds.
- [Errors](https://fathomcharts.com/en/docs/errors.md): Fathom Charts API error codes, identical over REST and the WebSocket, and how to handle each one.

## Indicators

- [Indicator catalog](https://fathomcharts.com/en/docs/indicators.md): Fathom Charts order flow indicators: parameters, data received and example messages.
- [Fathom Trades (`big-trades`)](https://fathomcharts.com/en/docs/indicators/big-trades.md): Large aggressive orders, rebuilt from consecutive trades.
- [Fathom Footprint (`footprint`)](https://fathomcharts.com/en/docs/indicators/footprint.md): Bid and ask volume at each price level, bar by bar.
- [Fathom Zones (`effort-zones`)](https://fathomcharts.com/en/docs/indicators/effort-zones.md): Directional effort zones on 40-tick range bars, with a moving average of the closes.
- [Fathom Walls (`liquidity-walls`)](https://fathomcharts.com/en/docs/indicators/liquidity-walls.md): Liquidity walls defended at repeated extremes.
- [Fathom Flow (`flow-tracker`)](https://fathomcharts.com/en/docs/indicators/flow-tracker.md): Accelerations, exhaustions, slowdowns and absorption levels.
- [Fathom Imbalances (`imbalances`)](https://fathomcharts.com/en/docs/indicators/imbalances.md): Stacked buyer and seller imbalances, turned into zones.
- [Fathom VWAP (`vwap-bands`)](https://fathomcharts.com/en/docs/indicators/vwap-bands.md): Session or rolling VWAP, with three bands.
- [Fathom Levels (`key-levels`)](https://fathomcharts.com/en/docs/indicators/key-levels.md): High, low, open, close, POC and value area of past sessions, weeks and months.
- [Fathom Profile (`session-profile`)](https://fathomcharts.com/en/docs/indicators/session-profile.md): Session POC, value area, VWAP and standard deviation, bar by bar.
- [Fathom Opening (`opening-range`)](https://fathomcharts.com/en/docs/indicators/opening-range.md): RTH opening range, breakout zones and statistical projections.

## API

- [Indicator catalog (JSON)](https://api.fathomcharts.com/v1/indicators): every indicator with the JSON Schemas of its parameters and of its data, no authentication.
- [Instruments (JSON)](https://api.fathomcharts.com/v1/instruments): tradable instruments and their tick size, with an API key.
- [Plans and limits (JSON)](https://api.fathomcharts.com/v1/offers): offers and the limits of each combination, no authentication.
- [OpenAPI 3.1](https://api.fathomcharts.com/docs/json): the REST API description.

## Optional

- [Documentation](https://fathomcharts.com/docs.md): Documentation de l’API Fathom Charts : des indicateurs order flow calculés côté serveur sur les futures, en temps réel par WebSocket ou sur l’historique en REST.
- [Démarrage rapide](https://fathomcharts.com/docs/demarrage-rapide.md): De la clé API au premier gros ordre reçu en temps réel, puis la même requête sur l’historique.
- [Authentification](https://fathomcharts.com/docs/authentification.md): Clés API Fathom Charts : clés de test et live, scopes et restrictions, rotation et révocation, accès au stream depuis un navigateur.
- [Utiliser avec un LLM](https://fathomcharts.com/docs/llm.md): Donnez la documentation Fathom Charts en Markdown à votre assistant IA ou à votre coding agent : llms.txt, pages Markdown et instructions prêtes à coller.
- [Temps réel (WebSocket)](https://fathomcharts.com/docs/websocket.md): Recevoir les indicateurs Fathom Charts en temps réel : connexion, subscription, snapshot initial, cursors et reprise après coupure, états du stream et reconnexion.
- [Historique](https://fathomcharts.com/docs/historique.md): Calculez un indicateur Fathom Charts sur une période passée : requête, pagination, estimation du coût et raccord avec le temps réel.
- [Exports](https://fathomcharts.com/docs/exports.md): Exportez un indicateur Fathom Charts sur une longue période : un fichier NDJSON compressé, reçu au fil du calcul et reprenable après une coupure.
- [Limites](https://fathomcharts.com/docs/limites.md): Limites de chaque offre Fathom Charts (connexions, subscriptions, historique, compute budget, exports), limites techniques de l’API et suivi de votre consommation.
- [Offres et facturation](https://fathomcharts.com/docs/facturation.md): Offres Fathom Charts : Sandbox gratuite, Live (abonnement mensuel, temps réel) et Historique (achat unique, accès à vie). Paiement par Stripe ou Creem selon votre pays, activation, résiliation et absence de remboursement.
- [Erreurs](https://fathomcharts.com/docs/errors.md): Codes d’erreur de l’API Fathom Charts, identiques en REST et sur le WebSocket, et comment réagir à chacun.
- [Catalogue des indicateurs](https://fathomcharts.com/docs/indicateurs.md): Les indicateurs order flow de Fathom Charts : paramètres, données reçues et exemples de messages.
- [Fathom Trades (`big-trades`)](https://fathomcharts.com/docs/indicateurs/big-trades.md): Les gros ordres agressifs, reconstitués à partir des trades consécutifs.
- [Fathom Footprint (`footprint`)](https://fathomcharts.com/docs/indicateurs/footprint.md): Volumes bid et ask par niveau de prix, barre par barre.
- [Fathom Zones (`effort-zones`)](https://fathomcharts.com/docs/indicateurs/effort-zones.md): Zones d'effort directionnel sur barres range de 40 ticks, avec la moyenne mobile des clôtures.
- [Fathom Walls (`liquidity-walls`)](https://fathomcharts.com/docs/indicateurs/liquidity-walls.md): Les murs de liquidité défendus sur des extrêmes répétés.
- [Fathom Flow (`flow-tracker`)](https://fathomcharts.com/docs/indicateurs/flow-tracker.md): Accélérations, épuisements, ralentissements et niveaux d'absorption.
- [Fathom Imbalances (`imbalances`)](https://fathomcharts.com/docs/indicateurs/imbalances.md): Les imbalances empilées entre acheteurs et vendeurs, transformées en zones.
- [Fathom VWAP (`vwap-bands`)](https://fathomcharts.com/docs/indicateurs/vwap-bands.md): VWAP de séance ou glissant, avec trois bandes.
- [Fathom Levels (`key-levels`)](https://fathomcharts.com/docs/indicateurs/key-levels.md): Plus haut, plus bas, ouverture, clôture, POC et value area des séances, semaines et mois.
- [Fathom Profile (`session-profile`)](https://fathomcharts.com/docs/indicateurs/session-profile.md): POC, value area, VWAP et écart-type de la séance, barre par barre.
- [Fathom Opening (`opening-range`)](https://fathomcharts.com/docs/indicateurs/opening-range.md): Opening range RTH, zones de sortie et projections statistiques.