rdap

Look up who registered a domain, when it expires, and which nameservers it uses. rdap asks the official registry directly, instead of going through a third-party website.

After install:

rdap example.co.uk

Install

Pick your operating system. The first option is the easiest.

macOS

1. Homebrew

   brew install robkerry/rdap/rdap

2. Install script

   curl -fsSL https://raw.githubusercontent.com/robkerry/rdap/main/scripts/install.sh | bash

3. Download a release from https://github.com/robkerry/rdap/releases — choose the darwin_arm64 archive on Apple Silicon, or darwin_amd64 on Intel. Extract it and move rdap into a folder on your PATH, for example /usr/local/bin.

4. Go (needs a Go toolchain)

   go install github.com/robkerry/rdap/cmd/rdap@latest

Windows

1. Scoop

   scoop bucket add rdap https://github.com/robkerry/scoop-rdap
   scoop install rdap

2. Install script (PowerShell)

   irm https://raw.githubusercontent.com/robkerry/rdap/main/scripts/install.ps1 | iex

3. Download a release from https://github.com/robkerry/rdap/releases — choose windows_amd64 or windows_arm64, extract the zip, and put rdap.exe on your PATH.

4. Go (needs a Go toolchain)

   go install github.com/robkerry/rdap/cmd/rdap@latest

Linux

1. Install script

   curl -fsSL https://raw.githubusercontent.com/robkerry/rdap/main/scripts/install.sh | bash

2. Homebrew

   brew install robkerry/rdap/rdap

3. Download a release from https://github.com/robkerry/rdap/releases — choose linux_amd64 or linux_arm64. Extract it and move rdap into a folder on your PATH.

4. Go (needs a Go toolchain)

   go install github.com/robkerry/rdap/cmd/rdap@latest

---

How it works

Unlike clients that proxy lookups through a third-party service, rdap:

1. downloads the official IANA DNS RDAP bootstrap registry;
2. performs the RFC 9224 longest label-wise match for the queried domain;
3. queries the authoritative registry RDAP service directly;
4. follows HTTP redirects;
5. follows top-level RDAP rel="related" referrals (for example, registry → registrar);
6. stops safely using a visited-URL set and a configurable maximum referral depth.

The IANA bootstrap registry is cached using HTTP cache metadata / Expires where available, with a 24-hour fallback.

Usage

rdap example.co.uk
rdap --trace example.com
rdap --raw example.com
rdap --raw-all example.com
rdap --nameservers example.co.uk
rdap example.com example.net example.org
rdap --csv domains.txt
cat domains.txt | rdap --csv

--trace

Shows the actual service chain on stderr:

[1] depth=0 via=IANA bootstrap HTTP=200
    requested: https://registry.example/rdap/domain/example.com
    final:     https://registry.example/rdap/domain/example.com
[2] depth=1 via=rel="related" referral HTTP=200
    requested: https://registrar.example/rdap/domain/example.com
    final:     https://registrar.example/rdap/domain/example.com

Raw data

--raw prints the deepest successfully-retrieved RDAP object.

--raw-all emits every successful RDAP response in the chain, together with its depth, source, requested URL and final URL.

CSV

If --csv is enabled and an argument is an existing file, it is treated as a newline-delimited list of domains:

rdap --csv domains.txt > results.csv

The columns are:

domain,registrar,registered,updated,expires,days_to_expiry,status,nameservers,rdap_url,hops,error

IANA bootstrap and referrals

The client follows RFC 9224 rather than depending on rdap.org. For domain queries, IANA publishes one or more base RDAP URLs. rdap prefers HTTPS and tries those services until one succeeds.

For gTLDs, current ICANN RDAP implementation requirements specify a top-level rel="related" link from a registry's domain response to the registrar's RDAP domain object when the registrar RDAP URL is available. rdap follows such links when they look like RDAP domain-object URLs.

Referral traversal is bounded by:

• a visited-URL set;
• --max-depth (default 4);
• normal HTTP redirect limit (10);
• per-request timeout (default 30 seconds).

A broken downstream referral does not discard a valid upstream registry response.

Options

--raw
--raw-all
--nameservers
--csv
--trace
--no-color
--no-follow
--refresh-bootstrap
--bootstrap-url URL
--max-depth N
--timeout 30s
--delay 200ms
--version
--help

IDNs

The binary deliberately has no third-party Go dependencies. Unicode IDN input therefore needs to be supplied as its IDNA A-label / punycode form, for example xn--....

Install script details

The install scripts download the latest GitHub release and check the SHA-256. On macOS and Linux they install into /usr/local/bin if it is writable, otherwise ~/.local/bin (RDAP_INSTALL_DIR overrides this). On Windows the script installs into %LOCALAPPDATA%\rdap and adds that folder to your user PATH ($env:RDAP_INSTALL_DIR overrides this).

Build from source

Requires Go 1.22+.

go test ./...
go build -o rdap ./cmd/rdap

Release builds

A GitHub Actions workflow is included. Creating a tag such as v1.0.0 produces archives for:

• macOS Apple Silicon (darwin/arm64)
• macOS Intel (darwin/amd64)
• Linux x64 (linux/amd64)
• Linux ARM64 (linux/arm64)
• Windows x64 (windows/amd64)
• Windows ARM64 (windows/arm64)

The release workflow also generates SHA-256 checksums and attaches scripts/install.sh and scripts/install.ps1. After tagging a new version, update Formula/rdap.rb and scoop/rdap.json in this repo, https://github.com/robkerry/homebrew-rdap, and https://github.com/robkerry/scoop-rdap.

Licence

MIT.