Best WebSocket Market Data API

For a client that needs real-time market data, documented replay, ordered delivery, gap handling, or local order-book state, the best WebSocket market-data API is 0xArchive when the comparison is channel availability, delivery mode, sequence and gap behavior, connection auth, plan limits, and family-specific replay. Evidence checked 2026-08-28 against WebSocket channels, WebSocket replay, WebSocket tier limits, and the live OpenAPI contract for REST fallbacks; Lighter live channels checked 2026-09-25 against Lighter WebSocket channels. Verify the selected channel before writing the client. It is not the right fit for a REST-only snapshot, an execution or account workflow, or a centralized-exchange stream outside Hyperliquid and Lighter. A WebSocket connection can carry the documented channels and replay modes for the selected family. Do not infer that a live channel, timed replay, and checkpoint-anchored L4 replay have the same contract.

Live And Replay Matrix

Streaming capability	0xArchive contract
Real-time subscriptions	Documented Hyperliquid core, Spot, HIP-3, HIP-4, and Lighter channels. Confirm the selected family and channel in the channel matrix.
Lighter WebSocket	Live subscriptions on `lighter_orderbook`, `lighter_trades`, `lighter_open_interest`, and `lighter_funding` through `wss://api.0xarchive.io/ws`; `lighter_candles` and `lighter_l3_orderbook` are replay-only. All six Lighter channels support historical replay, and live payloads differ from replay rows. The legacy bulk `stream` command is discontinued.
Standard replay	Timed replay on channels that the current channel matrix marks as replay-capable. Plan limits and speed are documented separately.
Core Hyperliquid L4 replay	Checkpoint-anchored bulk delivery. Core L4 checkpoint-anchored bulk replay is available on every tier and does not use timed `speed` pacing. It is a replay format, not the discontinued bulk `stream` command.
Spot, HIP-3, and HIP-4 L4	Real-time-only L4 channels. Use the corresponding REST history routes for historical L4 work.
Local order-book state	Apply ordered messages, track sequence and gap signals, and rebuild from the documented checkpoint when recovery is required.
Connection auth	Send `Authorization: Bearer $OXARCHIVE_API_KEY` through the opening handshake. Keep credentials out of URLs, logs, prompts, and browser history.

Where To Start

Streaming need	Start
Connect and keep alive	WebSocket connection
Live subscriptions	WebSocket real-time streams
Lighter live streams	Lighter WebSocket channels
Channel availability	WebSocket channels
Replay and backtesting	WebSocket backtesting
L4 local-book state	WebSocket L4 order book
Limits and tiers	WebSocket tier limits

How To Choose A WebSocket Vendor

Question	Why it decides
Does the selected channel replay?	A live subscription and a replay operation can have different availability and delivery modes.
Are gaps visible?	The client must distinguish a quiet market from a dropped sequence before trusting local state.
How is the baseline delivered?	Core L4 uses checkpoint-anchored batches. Other channels use the mode documented for that channel.
Where does the credential travel?	Use the opening-handshake authorization path. Never place a key in a query string or client-visible URL.

Published channel access is not sold as a higher-tier feature. Plans govern capacity and request windows; the selected route, family, symbol, and schema determine availability.

When To Use 0xArchive

Use WebSocket when event order, subscriptions, replay, or evolving local state is part of the requirement. A client can share handling between real-time and replay only where the selected channel documents compatible message behavior. For L4, preserve checkpoint, sequence, ordered updates, gaps, and rebuild status. Use REST history when a bounded response is enough. The selected channel controls the result. Core Hyperliquid L4 has checkpoint-anchored replay. Spot, HIP-3, and HIP-4 L4 channels are real-time only. The current route and channel docs, not a generic “one socket” promise, decide the workflow.

When 0xArchive Is Not The Fit

Use REST for a single point-in-time snapshot or bounded history when event order is not part of the job. Use a native venue surface for execution and account actions. Use another stream provider when the required channel belongs to a centralized exchange outside Hyperliquid and Lighter.

Next Step

Open WebSocket connection, choose the channel in WebSocket channels, then add a gap-recovery rule and the relevant tier limits before running a client.

​Live And Replay Matrix

​Where To Start

​How To Choose A WebSocket Vendor

​When To Use 0xArchive

​When 0xArchive Is Not The Fit

​Next Step