> ## Documentation Index > Fetch the complete documentation index at: https://cosmos-docs-sync-security-docs.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # blockchain > Get block headers (max: 20) for minHeight <= height <= maxHeight. Get block headers for minHeight <= height <= maxHeight. At most 20 items will be returned. Upon success, the `Cache-Control` header will be set with the default maximum age. ## OpenAPI ````yaml /cometbft/latest/api-reference/rpc/openapi.yaml get /blockchain openapi: 3.0.0 info: title: CometBFT RPC contact: name: CometBFT url: https://docs.cosmos.network/cometbft description: > CometBFT supports the following RPC protocols: * URI over HTTP * JSONRPC over HTTP * JSONRPC over websockets ## Configuration RPC can be configured by tuning parameters under `[rpc]` table in the `$CMTHOME/config/config.toml` file or by using the `--rpc.X` command-line flags. The default RPC listen address is `tcp://127.0.0.1:26657`. To set another address, set the `laddr` config parameter to desired value. CORS (Cross-Origin Resource Sharing) can be enabled by setting `cors_allowed_origins`, `cors_allowed_methods`, `cors_allowed_headers` config parameters. If testing using a local RPC node, under the `[rpc]` section change the `cors_allowed_origins` property, please add the URL of the site where this OpenAPI document is running, for example: `cors_allowed_origins = ["http://localhost:8088"]` or if testing from the official documentation site: `cors_allowed_origins = ["https://docs.cosmos.network"]` ## Arguments Arguments which expect strings or byte arrays may be passed as quoted strings, like `"abc"` or as `0x`-prefixed strings, like `0x616263`. ## URI/HTTP A REST like interface. curl localhost:26657/block?height=5 ## JSONRPC/HTTP JSONRPC requests can be POST'd to the root RPC endpoint via HTTP. curl --header "Content-Type: application/json" --request POST --data '{"method": "block", "params": ["5"], "id": 1}' localhost:26657 ## JSONRPC/websockets JSONRPC requests can be also made via websocket. The websocket endpoint is at `/websocket`, e.g. `localhost:26657/websocket`. Asynchronous RPC functions like event `subscribe` and `unsubscribe` are only available via websockets. For example using the [websocat](https://github.com/vi/websocat) tool, you can subscribe for 'NewBlock` events with the following command: echo '{ "jsonrpc": "2.0","method": "subscribe","id": 0,"params": {"query": "tm.event='"'NewBlock'"'"} }' | websocat -n -t ws://127.0.0.1:26657/websocket version: v0.38.x license: name: Apache 2.0 url: https://github.com/cometbft/cometbft/blob/v0.38.x/LICENSE servers: - url: https://rpc.cosmos.directory/cosmoshub description: Interact with the CometBFT RPC from a public node in the Cosmos registry - url: http://localhost:26657 description: Interact with CometBFT RPC node running locally security: [] tags: - name: Info description: Informations about the node APIs - name: Tx description: Transactions broadcast APIs - name: ABCI description: ABCI APIs - name: Evidence description: Evidence APIs - name: Unsafe description: Unsafe APIs paths: /blockchain: get: tags: - Info summary: blockchain description: |- Get block headers (max: 20) for minHeight <= height <= maxHeight. Get block headers for minHeight <= height <= maxHeight. At most 20 items will be returned. Upon success, the `Cache-Control` header will be set with the default maximum age. operationId: blockchain parameters: - in: query name: minHeight description: Minimum block height to return schema: type: integer example: 1 - in: query name: maxHeight description: Maximum block height to return schema: type: integer example: 2 responses: '200': description: Block headers, returned in descending order (highest first). content: application/json: schema: $ref: '#/components/schemas/BlockchainResponse' '500': description: Error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: BlockchainResponse: description: Blockchain info allOf: - $ref: '#/components/schemas/JSONRPC' - type: object properties: result: $ref: '#/components/schemas/Blockchain' ErrorResponse: description: Error Response allOf: - $ref: '#/components/schemas/JSONRPC' - type: object properties: error: type: string example: Description of failure JSONRPC: type: object properties: id: type: integer example: 0 jsonrpc: type: string example: '2.0' Blockchain: type: object required: - last_height - block_metas properties: last_height: type: string example: '1276718' block_metas: type: array items: $ref: '#/components/schemas/BlockMeta' BlockMeta: type: object properties: block_id: $ref: '#/components/schemas/BlockID' block_size: type: integer example: 1000000 header: $ref: '#/components/schemas/BlockHeader' num_txs: type: string example: '54' BlockID: required: - hash - parts properties: hash: type: string example: 112BC173FD838FB68EB43476816CD7B4C6661B6884A9E357B417EE957E1CF8F7 parts: required: - total - hash properties: total: type: integer example: 1 hash: type: string example: 38D4B26B5B725C4F13571EFE022C030390E4C33C8CF6F88EDD142EA769642DBD type: object BlockHeader: required: - version - chain_id - height - time - last_block_id - last_commit_hash - data_hash - validators_hash - next_validators_hash - consensus_hash - app_hash - last_results_hash - evidence_hash - proposer_address properties: version: required: - block - app properties: block: type: string example: '10' app: type: string example: '0' type: object chain_id: type: string example: cosmoshub-2 height: type: string example: '12' time: type: string example: '2019-04-22T17:01:51.701356223Z' last_block_id: $ref: '#/components/schemas/BlockID' last_commit_hash: type: string example: 21B9BC845AD2CB2C4193CDD17BFC506F1EBE5A7402E84AD96E64171287A34812 data_hash: type: string example: 970886F99E77ED0D60DA8FCE0447C2676E59F2F77302B0C4AA10E1D02F18EF73 validators_hash: type: string example: D658BFD100CA8025CFD3BECFE86194322731D387286FBD26E059115FD5F2BCA0 next_validators_hash: type: string example: D658BFD100CA8025CFD3BECFE86194322731D387286FBD26E059115FD5F2BCA0 consensus_hash: type: string example: 0F2908883A105C793B74495EB7D6DF2EEA479ED7FC9349206A65CB0F9987A0B8 app_hash: type: string example: 223BF64D4A01074DC523A80E76B9BBC786C791FB0A1893AC5B14866356FCFD6C last_results_hash: type: string example: '' evidence_hash: type: string example: '' proposer_address: type: string example: D540AB022088612AC74B287D076DBFBC4A377A2E type: object ````