# Voting Ledger Snapshots

The Catalyst team provides access to routine snapshots of the blockchain state. These snapshots are automatically taken at 1-hour intervals and uploaded to a persistent storage system in the form of an archive. Currently, these archives can be found by [querying the Archive API](https://archiver.projectcatalyst.io/api/v1/archives/). You can learn more about the available endpoints by inspecting the [Swagger documentation](https://archiver.projectcatalyst.io/swagger/index.html).

To show an example of how to interact with the API and download an archive, we will use the `curl` and `jq` CLI tools. First, we must list the available archives:

```
> curl -s https://archiver.projectcatalyst.io/api/v1/archives/ | jq
{
  "next": "",
  "archives": [
    {
      "id": "019fd6b2-c36b-419f-8a2d-ebf06b91a762",
      "size": 364315029,
      "compression": "zstd",
      "packaging": "tar",
      "metadata": {
        "epoch": "1952",
        "fund": "fund10",
        "slot": "14",
        "timestamp": "2023-08-29T18:00:59Z"
      }
    },
    {
      "id": "64c56031-56ab-43dd-a1ca-138a85298d2b",
      "size": 372405154,
      "compression": "zstd",
      "packaging": "tar",
      "metadata": {
        "epoch": "1954",
        "fund": "fund10",
        "slot": "17",
        "timestamp": "2023-08-29T20:01:09Z"
      }
    },
    {
      "id": "ad16b160-0cc2-4252-ae61-f468c95cbf29",
      "size": 364453534,
      "compression": "zstd",
      "packaging": "tar",
      "metadata": {
        "epoch": "1953",
        "fund": "fund10",
        "slot": "23",
        "timestamp": "2023-08-29T19:01:34Z"
      }
    }
  ]
}
```

In the above response, there are only three archives available. Should the number of results exceed 50, they will automatically be paginated. This is made evident by the `next` field being set. To fetch subsequent archives, you would call the same endpoint and append `?next={VALUE}` where `VALUE` is the value of the `next` field. To iterate over all available archives, you can repeat this process until the `next` field is empty.

For this example, we'll choose to fetch the first archive in the list. To get a link for downloading the archive, we can run:

```
> curl -q https://archiver.projectcatalyst.io/api/v1/archives/019fd6b2-c36b-419f-8a2d-ebf06b91a762/download | jq
{
  "url": "https://archives.projectcatalyst.io/prod/019fd6b2-c36b-419f-8a2d-ebf06b91a762?Expires=1693341938&Signature=R5CJdg4GZCHHGakePZJIHaYHSOthO-RuIAuiGwcLTnD3MZrtxUMWQFvLdSpWrl6dqPB6VNNeS5sMp9pK7x-JmuBvnZ3XZNUEcBA9XLlMgIZJQDD7l6JEgCtKWRiOFPbOSUZSLQMhD6mbL2koARzdZjkzLDjPFFf33~vU89qZzt-VaaMseDUtGv-6zU6ANh2RkUvWD9UCUDTwoU9VjrMhwPfrx2kaWGIkt5a3NqxkNmti7SVdwtcsKWN7wuLQNaks-PJnrTKwtp7Qc8Ll3vrf846vJWzH3UVDwDB0vbk1nVcysijEaj6m7DcWA5TR7Di84FHjYf9zmTJYeeC71Ht8mw__&Key-Pair-Id=K36UOCCH06A5FV"
}
```

This endpoint returns a time-sensitive URL to download the archive. Note that this URL is only valid for 15 minutes. To download the archive:

```
> URL="$(curl -s https://archiver.projectcatalyst.io/api/v1/archives/019fd6b2-c36b-419f-8a2d-ebf06b91a762/download | jq -r .url)"
> curl -o archive.tar.zstd "$URL"
```

We save the file as a `.tar.zstd` archive because this is how the contents were archived. If you look back at the API response, you'll see the `compression` and `packaging` fields were set to `zstd` and `tar` respectively. We can use these fields to determine the process for extracting the archive. To extract the contents, we'll need to use the `tar` and `zstd` CLIs:

```
> zstd -d archive.tar.zstd && tar -xvf archive.tar
archive.tar.zstd    : 523103232 bytes
artifacts
artifacts/block0.bin
permanent
permanent/blocks
permanent/blocks/data
permanent/blocks/seqno
permanent/chain_length
permanent/chain_length/data
permanent/chain_length/seqno
volatile
volatile/blobs
volatile/conf
volatile/db
volatile/snap.00000003A7319A1C
```

We now have a complete snapshot of the blockchain state on our local filesytem.<br>