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Lark exposes a REST API for reading and writing data over plain HTTP. If you’re working from a server, a script, a CLI tool, or any environment where you don’t want to maintain a persistent connection, the REST API is the way to go. The REST API is fully compatible with the Firebase Realtime Database REST API. If you have existing code that hits Firebase’s /.json endpoints, it works with Lark by changing the hostname.

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URL format

Every REST request targets a path in your database, with .json appended: 
https://{projectId}.larkdb.net/{database}/{path}.json
For example, to access /players/alice in the my-game database of project chess-app: 
https://chess-app.larkdb.net/my-game/players/alice.json
The root of a database: 
https://chess-app.larkdb.net/my-game/.json

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Database-in-subdomain format

You can also specify the database as part of the subdomain using --: 
https://{database}--{projectId}.larkdb.net/{path}.json

https://my-game--chess-app.larkdb.net/players/alice.json
If you’re migrating a legacy Firebase application, you’ll likely want to use the database-in-subdomain format so you don’t have to change your URLs.

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Authentication

Pass an auth token as a query parameter: 
GET https://chess-app.larkdb.net/my-game/players.json?auth=YOUR_TOKEN
The auth parameter accepts any token that Lark supports — Lark tokens (HS256 JWTs signed with your secret key) or Firebase Auth tokens. You can also use access_token as an alias: 
GET https://chess-app.larkdb.net/my-game/players.json?access_token=YOUR_TOKEN
If you omit the token, the request is treated as anonymous. Your security rules determine what anonymous clients can access.

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Operations at a glance

HTTP methodOperationDescription
GETReadFetch data at a path
PUTSetReplace data at a path
POSTPushAdd a child with an auto-generated key
PATCHUpdateMerge data at a path
DELETERemoveDelete data at a path

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When to use the REST API

  • Server-side operations — Read or write data from your backend without maintaining a WebSocket connection.
  • One-off scripts — Import data, seed a database, or run migrations.
  • Webhooks and integrations — Receive a webhook, write to Lark with a single HTTP call.
  • Environments without WebSocket support — Edge functions, serverless workers, or constrained runtimes.
  • Debugging — Quick reads with curl to inspect your data.
For real-time subscriptions and persistent connections, use the Lark SDK or Firebase SDKs instead.

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Quick example

# Write data
curl -X PUT \
  'https://chess-app.larkdb.net/my-game/players/alice.json?auth=YOUR_TOKEN' \
  -d '{"name": "Alice", "score": 0}'

# Read it back
curl 'https://chess-app.larkdb.net/my-game/players/alice.json?auth=YOUR_TOKEN'
# {"name":"Alice","score":0}

# Update a single field
curl -X PATCH \
  'https://chess-app.larkdb.net/my-game/players/alice.json?auth=YOUR_TOKEN' \
  -d '{"score": 42}'

# Push a new child with auto-generated key
curl -X POST \
  'https://chess-app.larkdb.net/my-game/messages.json?auth=YOUR_TOKEN' \
  -d '{"text": "Hello!", "sender": "alice"}'
# {"name":"-Kabc123xyz"}

# Delete data
curl -X DELETE \
  'https://chess-app.larkdb.net/my-game/players/alice.json?auth=YOUR_TOKEN'

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What’s next

Reading data

GET requests, shallow reads, queries, and formatting options.

Writing data

PUT, POST, PATCH, DELETE, multi-path updates, and server values.

Streaming

Server-Sent Events for real-time updates over HTTP.

Conditional requests

ETags and compare-and-swap for safe concurrent writes.