# Cardano Chain API
> Read live Cardano chain economics and epoch data from the public Koios indexer — no key — focused on the network-wide view that stake-account and asset readers miss. The tip endpoint returns the chain head: the current epoch, block height and slot. The epoch endpoint returns any epoch's activity — blocks produced, total transactions, total output and fees (in ADA) and the active stake securing it, with its start and end. And the supply endpoint returns Cardano's ADA monetary breakdown: total supply, circulating, reserves (still to be issued), treasury (the on-chain governance fund) and the reward pot, against the fixed 45-billion-ADA cap. The chain-economics layer every Cardano wallet, explorer, staker and analytics tool needs. Live from the indexer; short cache only.

## Authentication
All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys.

```bash
curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/cardanochain-api/..."
```

## Pricing
- **Free** (Free) — 6,500 calls/Mo, 3 req/s
- **Starter** ($9/Mo) — 123,000 calls/Mo, 8 req/s
- **Pro** ($34/Mo) — 750,000 calls/Mo, 20 req/s
- **Business** ($96/Mo) — 4,725,000 calls/Mo, 50 req/s

## Endpoints

### Cardano

#### `GET /v1/epoch` — Epoch activity: blocks, transactions, output, fees, active stake

**Parameters:**
- `epoch` (query, optional, string) — Epoch number (omit for current) Example: `637`

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/cardanochain-api/v1/epoch?epoch=637"
```

**Response:**
```json
{
    "data": {
        "note": "Activity for the epoch: blocks produced, transaction count, total output and fees (in ADA), and the active stake securing it.",
        "epoch": 637,
        "blocks": 1805,
        "source": "Koios",
        "end_time": 1781819091,
        "start_time": 1781387091,
        "transactions": 7400,
        "total_fees_ada": 2283.328435,
        "active_stake_ada": 21609933343.537888,
        "first_block_time": 1781387095,
        "total_output_ada": 2586830311.082343
    },
    "meta": {
        "timestamp": "2026-06-14T08:03:52.410Z",
        "request_id": "4233ede8-6309-490e-b383-fa7a3e0fe65d"
    },
    "status": "ok",
    "message": "Epoch retrieved successfully",
    "success": true
}
```

#### `GET /v1/supply` — ADA monetary breakdown: supply, circulating, reserves, treasury, rewards

**Parameters:**
- `epoch` (query, optional, string) — Epoch number (omit for current) Example: `637`

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/cardanochain-api/v1/supply?epoch=637"
```

**Response:**
```json
{
    "data": {
        "note": "Cardano's ADA monetary breakdown for the epoch: total supply, circulating, reserves (unissued), treasury (governance funds) and the reward pot. Max supply is 45,000,000,000 ADA.",
        "epoch": 637,
        "source": "Koios",
        "reserves_ada": 6307350175.048889,
        "treasury_ada": 1486632640.502068,
        "max_supply_ada": 45000000000,
        "reward_pot_ada": 826656960.494501,
        "circulating_ada": 36373183721.42929,
        "total_supply_ada": 38692649824.95111
    },
    "meta": {
        "timestamp": "2026-06-14T08:03:53.203Z",
        "request_id": "f3ac577e-ee26-44cd-a4f9-dfe293303e5f"
    },
    "status": "ok",
    "message": "Supply retrieved successfully",
    "success": true
}
```

#### `GET /v1/tip` — Chain head: current epoch, block height and slot

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/cardanochain-api/v1/tip"
```

**Response:**
```json
{
    "data": {
        "note": "The Cardano chain head: current epoch, slot and block.",
        "epoch": 637,
        "source": "Koios",
        "block_hash": "881bdf58821581fe82beb8c586d6286d8ca0d843c31e885aaf82c38a66dc4a20",
        "block_time": 1781424230,
        "epoch_slot": 37139,
        "block_height": 13548077,
        "absolute_slot": 189857939
    },
    "meta": {
        "timestamp": "2026-06-14T08:03:53.572Z",
        "request_id": "72774610-ff00-484c-8ec6-18bee8b3ddc5"
    },
    "status": "ok",
    "message": "Tip retrieved successfully",
    "success": true
}
```

### Meta

#### `GET /v1/meta` — Service metadata & live sample

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/cardanochain-api/v1/meta"
```

**Response:**
```json
{
    "data": {
        "sample": {
            "epoch": 637,
            "block_height": 13548077
        },
        "source": "public Koios API (api.koios.rest), keyless",
        "service": "cardanochain-api",
        "endpoints": {
            "GET /v1/tip": "Chain head: current epoch, block height and slot.",
            "GET /v1/meta": "This document.",
            "GET /v1/epoch": "Epoch activity: blocks, transactions, output, fees, active stake (optional epoch).",
            "GET /v1/supply": "ADA monetary breakdown: supply, circulating, reserves, treasury, rewards (optional epoch)."
        },
        "description": "Read live Cardano chain economics and epoch data from the public Koios indexer: the chain tip (epoch/block/slot), any epoch's activity (blocks/transactions/output/fees/active stake), and the ADA monetary breakdown (supply/circulating/reserves/treasury/reward pot). The chain-economics layer for Cardano wallets, explorers and stakers. Live, short cache only.",
        "upstream_status": "ok"
    },
    "meta": {
        "timestamp": "2026-06-14T08:03:53.667Z",
        "request_id": "b2bb6322-90d6-4d87-afa8-7f0d5279fbcf"
    },
    "status": "ok",
    "message": "Meta",
    "success": true
}
```


---
Marketplace page: https://www.oanor.com/api/cardanochain-api
OpenAPI spec: https://www.oanor.com/api/cardanochain-api/openapi.json