Look up any AS or IP prefix at Lens by ipverse to explore announced prefixes and metadata.

Daily-updated datasets of autonomous systems (AS) with active BGP prefix announcements. Only includes AS that have announced at least one prefix within the last 90 days. No APIs, no databases - just simple file downloads.

Each AS gets its own directory with aggregated IPv4 and IPv6 prefixes in both JSON and plaintext formats. Prefixes are aggregated (adjacent and overlapping CIDR blocks are merged into larger blocks where possible). Perfect for firewall rules, network analysis, or tracking what IP ranges belong to specific organizations. Git history lets you see how an AS's announcements change over time.

• 2026-02-08: Added category and networkRole fields to JSON metadata
• 2026-01-17: Added bulk download archive in releases
• 2026-01-08: AS directories are now removed if no prefixes have been announced in the last 90 days. Historical metadata for removed AS may still be available in as-metadata.
• 2026-01-05: Removed lastAnnounced field to reduce git delta size. This field is still available in as-metadata.
• 2026-01-03: Repository renamed to as-ip-blocks, JSON format changed (subnets → prefixes, metadata nested).
• 2025-08-03: Removed opinionated handle cleanup
• 2023-09-03: Removed PEM certificates from description field

JSON and plaintext

JSON format (includes both IPv4 and IPv6):

{
  "asn": 1234,
  "metadata": {
    "handle": "FORTUM",
    "description": "Fortum",
    "countryCode": "FI",
    "country": "Finland",
    "origin": "authoritative",
    "category": "business",
    "networkRole": "stub"
  },
  "prefixes": {
    "ipv4": [
      "132.171.0.0/16",
      "137.96.0.0/16",
      "193.110.32.0/21"
    ],
    "ipv6": [
      "2405:1800::/32"
    ]
  }
}

Plaintext format (AS1234 IPv4):

# AS1234 (FORTUM)
# Fortum
#
132.171.0.0/16
137.96.0.0/16
193.110.32.0/21

Plaintext format (AS1234 IPv6):

# AS1234 (FORTUM)
# Fortum
#
2405:1800::/32

See as-metadata for metadata field descriptions and possible values.

Download the announced prefixes for a specific autonomous system:

AS1234 in JSON format:

curl https://raw.githubusercontent.com/ipverse/as-ip-blocks/master/as/1234/aggregated.json

AS1234 IPv4 addresses:

curl https://raw.githubusercontent.com/ipverse/as-ip-blocks/master/as/1234/ipv4-aggregated.txt

AS1234 IPv6 addresses:

curl https://raw.githubusercontent.com/ipverse/as-ip-blocks/master/as/1234/ipv6-aggregated.txt

Download all AS data in a single archive from the latest release:

curl -LO https://github.com/ipverse/as-ip-blocks/releases/latest/download/as-ip-blocks.tar.gz
tar -xzf as-ip-blocks.tar.gz

For the complete AS metadata dataset and field documentation, see as-metadata.

If you plan to use the routing data for firewalling purposes, have a look at:

• nftables-blacklist - nftables based Bash script
• ipverse-tools-crowdsec - Ban prefixes using Crowdsec's cscli command

• Block entire AS at the firewall (goodbye spam-friendly hosting providers)
• Check what routes an AS is announcing (Git history lets you track changes over time)
• Network research and statistical analysis
• Threat hunting and security research
• Figure out which IPs belong to a specific organization
• Pretty much anything where you need to map ASNs to their announced prefixes

• as-metadata: Complete AS metadata including lastAnnounced timestamps and additional fields not included in the per-AS files here.

Head over to the feedback repository if you have questions, issues, or suggestions.

This data is released under CC0 1.0 Universal.