# GET /v1/solana/health

Whether Solana data is currently being served: latest probe status and finalized slot.

## Purpose

Reports the result of the latest stored probe (`up`, `down`, `unknown`) with its finalized slot and latency, without calling Solana. The status is `unavailable` while Solana data is not configured on this service, and `unknown` before the first probe is stored; in both cases `slot` is null and `meta.slot` is 0 because there is no finalized slot to report. It does not name the upstream provider.

## When to use

Before relying on the Solana verdict endpoints, or to explain a 503 from them.

## When not to use

Not a measure of the Solana network itself, only of this service's access to it; use the latest-slot endpoint to see chain progress.

## Parameters

This endpoint takes no parameters.

## Request example

```sh
curl -s "https://api.criptonlabs.com/v1/solana/health"
```

## Response example (200)

```json
{
  "status": "up",
  "slot": 456943158,
  "latency_ms": 180,
  "last_probe_at": "2026-10-14T12:00:00.000Z",
  "meta": {
    "slot": 456943158,
    "commitment": "finalized",
    "as_of": "2026-10-14T12:00:03.000Z",
    "age_seconds": 1,
    "cache": "hit",
    "stale": false
  }
}
```

## Errors

- 429 [rate-limited](https://api.criptonlabs.com/errors/rate-limited.md)
- 503 [upstream-unavailable](https://api.criptonlabs.com/errors/upstream-unavailable.md)

## Caching

Fresh for 4 seconds; on upstream failure the last good value is served for up to 60 seconds (`meta.stale` is `true`), then the service answers 503. See the [freshness guide](https://api.criptonlabs.com/docs/guides/freshness.md).

## Rate limit

Tier `cheap`. See the [rate-limits guide](https://api.criptonlabs.com/docs/guides/rate-limits.md).

## MCP tool

The MCP tool `solana_network_health` returns the same data. See the [MCP quickstart](https://api.criptonlabs.com/docs/guides/mcp-quickstart.md).