> ## Documentation Index > Fetch the complete documentation index at: https://nexus.gerowallet.io/docs/llms.txt > Use this file to discover all available pages before exploring further. # Get UTXOs by references > Retrieve specific UTXOs by their transaction hash and output index. Accepts a list of 1-100 UTXO references (txHash + outputIndex) and returns the corresponding UTXO details including address, value, assets, and datum information. ## OpenAPI ````yaml https://nexus.gerowallet.io/v3/api-docs post /api/transactions/utxos openapi: 3.1.0 info: title: Nexus API description: >- Multi-chain blockchain data API for Cardano (and Apex), Bitcoin, and Midnight. ## Blockchains & Networks Endpoints are grouped by **blockchain**. Pick the target **network** with the `network` query parameter. A network is an environment *within* a blockchain, not a separate endpoint family. - **Cardano & Apex**: one shared set of UTxO endpoints serves `cardano-mainnet`, `cardano-preprod`, `cardano-preview`, `apex-prime-mainnet`, `apex-vector-mainnet`, `apex-vector-testnet` - **Bitcoin**: `bitcoin-mainnet`, `bitcoin-testnet4` - **Midnight**: `midnight-mainnet`, `midnight-preprod`, `midnight-preview` ### Key scope: one chain, one network Each API key is scoped to **one chain and one network**, fixed at creation time. A `cardano-mainnet` key cannot query `cardano-preprod`, and it cannot query Bitcoin or Midnight at all. Create one key per chain and network under the same account. Sending a `network` value that does not match the key returns **400 Network Mismatch**; omit the parameter and the request runs against the key's own network. What is uniform across chains is the integration surface, not the credential: one account, one base URL, one auth header, one docs site. ## Authentication Send your API key in the `X-Api-Key` header. This is the credential for programmatic access (create one in the dashboard; keys start with `nxs_`). `Authorization: Bearer ` is only for JWT **session** tokens issued by `/api/auth/login` (browser/mobile apps), not for API keys. ## Add-ons Capability is gated separately from network scope. Market data, wallet analytics, transaction building, MCP, and IPFS are paid add-ons; those endpoints return **402 Payment Required** on a key whose plan does not carry the matching add-on, even when the chain and network match. contact: name: Gero Wallet Team url: https://gerowallet.io email: support@gerowallet.io license: name: Apache 2.0 url: https://www.apache.org/licenses/LICENSE-2.0.html version: 1.0.0 servers: - url: https://nexus.gerowallet.io description: API Server security: - apiKeyAuth: [] - bearerAuth: [] tags: - name: Cardano · Blocks description: Cardano Block API - name: Cardano · Policy description: Cardano Policy API - name: IPFS description: IPFS Content Resolution API - name: Bitcoin · Ordinals description: Ordinals + runes metadata (ord indexer) - name: Cardano · Transactions description: Cardano Transactions API - name: Midnight · Transactions description: Midnight-specific transaction endpoints (unshielded UTXOs) - name: Bitcoin · Mempool description: Bitcoin mempool snapshot - name: Midnight · DUST description: DUST registration + generation status - name: Cardano · Stake Pools description: >- Cardano stake pool information including registrations, retirements, and pool metadata - name: Cardano · Network description: Cardano Network API - Query static network / genesis parameters - name: Cardano · Addresses description: Cardano Address API - name: Bitcoin · Addresses description: >- Bitcoin address-keyed queries: stats / balance / UTxOs via electrs; ordinals via ord - name: Bitcoin · Transactions description: Bitcoin transaction lookup and submission - name: Cardano · Governance description: >- Cardano on-chain governance: DReps, governance actions + votes, constitutional committee, constitution - name: Cardano · DReps description: >- Cardano delegate representatives (DReps): voting power, status, metadata, delegators - name: Cardano · Transaction Builder description: >- Cardano transaction building API. Builds unsigned transactions server-side for client-side signing and submission. Network can be specified in the request body or as a query parameter. Body takes precedence over query parameter. - name: Cardano · Assets description: Cardano Asset API - name: Cardano · Accounts description: Cardano Account API - name: Bitcoin · Fees description: Bitcoin fee-rate estimates by confirmation block target - name: Bitcoin · Blocks description: Bitcoin block lookup - name: Cardano Market Data description: Endpoints from cardano-market-data - name: Midnight · Indexer description: Transparent proxy to the Midnight GraphQL indexer - name: Cardano · Scripts description: Cardano script & datum API - name: Cardano · Epochs description: Cardano Epoch API - Query protocol parameters and epoch information - name: Bitcoin · Chain description: Bitcoin chain-tip and sync state paths: /api/transactions/utxos: post: tags: - Cardano · Transactions summary: Get UTXOs by references description: >- Retrieve specific UTXOs by their transaction hash and output index. Accepts a list of 1-100 UTXO references (txHash + outputIndex) and returns the corresponding UTXO details including address, value, assets, and datum information. operationId: getUtxos parameters: - name: network in: query required: false schema: type: string enum: - CARDANO_MAINNET - CARDANO_PREPROD - CARDANO_PREVIEW - APEX_PRIME_MAINNET - APEX_VECTOR_MAINNET - APEX_VECTOR_TESTNET - MIDNIGHT_MAINNET - MIDNIGHT_PREPROD - MIDNIGHT_PREVIEW - BITCOIN_MAINNET - BITCOIN_TESTNET4 requestBody: content: application/json: schema: type: array items: $ref: '#/components/schemas/UtxoRequestItem' required: true responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/UtxoDto' additionalProperties: default: '' default: '' '400': description: Bad request - invalid input or list size exceeds limit (1-100 items) content: application/json: schema: type: string additionalProperties: default: '' default: '' example: error: UTXO list must contain between 1 and 100 items '404': description: UTXO not found content: application/json: schema: type: string additionalProperties: default: '' default: '' example: error: UTXO not found '500': description: Internal server error content: application/json: schema: type: string additionalProperties: default: '' default: '' example: error: Internal server error components: schemas: UtxoRequestItem: type: object default: null description: UTXO reference for fetching specific transaction outputs properties: txHash: type: string default: '' description: Transaction hash containing the UTXO example: 8f83b73e8e7f4b7d8f9c2e8f83b73e8e7f4b7d8f9c2e8f83b73e8e7f4b7d8f9c maxLength: 64 minLength: 64 pattern: ^[a-fA-F0-9]{64}$ outputIndex: type: integer format: int32 default: '' description: Output index within the transaction (0-based) example: 0 minimum: 0 required: - outputIndex - txHash UtxoDto: type: object properties: collateral: type: boolean reference: type: boolean tx_hash: type: string output_index: type: integer format: int32 owner_addr: type: string owner_stake_addr: type: string owner_payment_credential: type: string owner_stake_credential: type: string amounts: type: array items: $ref: '#/components/schemas/AmountDto' lovelace_amount: type: integer format: int64 data_hash: type: string inline_datum: type: string inline_datum_json: type: object additionalProperties: {} reference_script_hash: type: string script_ref: type: string block_number: type: integer format: int64 block_time: type: integer format: int64 slot: type: integer format: int64 block_hash: type: string epoch: type: integer format: int32 consumed_by_tx: type: string is_collateral_return: type: boolean AmountDto: type: object properties: unit: type: string quantity: type: string policy_id: type: string asset_name: type: string securitySchemes: apiKeyAuth: type: apiKey description: >- ### API key (programmatic access — recommended) Send your API key in the `X-Api-Key` header. Keys start with `nxs_` and are created in the dashboard (or via **POST /api/keys** with a session JWT). Each key is scoped to **one chain and one network** (for example `cardano-mainnet`), fixed at creation time. It cannot query a different network on the same chain, and it cannot query a different chain at all. A mismatched `network` parameter returns **400 Network Mismatch**. Create one key per chain and network under the same account. This is the credential most integrations should use. name: X-Api-Key in: header bearerAuth: type: http description: >- ### JWT session token (browser / mobile apps) A short-lived JWT issued by `/api/auth/login` or `/api/auth/device`, sent as `Authorization: Bearer `. This is the **session** credential for the web dashboard and mobile apps, not for server-to-server API access. For programmatic API access use an **API key** in the `X-Api-Key` header instead — do **not** put an `nxs_` API key in this Bearer field. scheme: bearer bearerFormat: JWT ````