http2rdap

RDAP-over-HTTP — Fast & lightweight HTTP gateway that serves RDAP queries as a JSON REST API.

Built in Go, it accepts a POST request with a target (domain, IP address or ASN) and returns the parsed RDAP record as structured JSON. The authoritative RDAP server is discovered automatically via the IANA bootstrap registry (RFC 9224). The binary embeds a static web UI and an OpenAPI specification, with zero runtime dependencies.

Screenshot

The embedded web UI (served at /) provides an interactive form to issue RDAP queries and inspect responses directly in the browser. It supports dark and light themes and is fully translated into 15 languages.

Releases

Provided binaries are fully functional natively on Linux (amd64 or arm64), Windows (amd64), macOS (amd64 or arm64), and also via Docker (amd64 or arm64), with no additional dependencies required. For download and installation, please refer to the Releases page.

Disclaimer

This project is released as-is, for demonstration or reference purposes. It is not maintained: no bug fixes, dependency updates, or new features are planned. Issues and pull requests will not be addressed.

License

This project is licensed under the Apache License, Version 2.0 — see the LICENSE file for details.

Copyright (c) 2026 letstool.net

Features

Single static binary — no external runtime dependencies
Embedded web UI and OpenAPI 3.0 specification (/openapi.json)
Web UI available in dark and light mode, switchable at runtime via a toggle
Web UI fully translated into 15 languages: Arabic, Bengali, Chinese, German, English, Spanish, French, Hindi, Indonesian, Japanese, Korean, Portuguese, Russian, Urdu, Vietnamese
Supports domain names, IPv4 / IPv6 addresses, and AS numbers
Automatic RDAP server discovery via the IANA bootstrap registry (RFC 9224)
Bootstrap data cached locally with a 24-hour TTL (configurable directory via TEMP_DIR)
Returns fully structured and parsed RDAP data (registrar, dates, name servers, contacts, network ranges, DNSSEC, …)
Raw RDAP JSON included alongside parsed fields
Configurable listen address, RDAP timeout, and HTTP request deadline
Docker image built on scratch — minimal attack surface

Build

Prerequisites

Go 1.24+

Native binary (Linux)

bash scripts/linux_build.sh

The binary is output to ./out/http2rdap.

The script produces a fully static binary (no libc dependency):

go build \
    -mod=vendor \
    -trimpath \
    -ldflags="-extldflags -static -s -w" \
    -tags netgo \
    -o ./out/http2rdap ./cmd/http2rdap

Windows

scripts\windows_build.cmd

Docker image

bash scripts/docker_build.sh

This runs a two-stage Docker build:

Builder — golang:1.24-alpine compiles a static binary
Runtime — scratch image, containing only the binary

The resulting image is tagged letstool/http2rdap:latest.

Run

Native (Linux)

bash scripts/linux_run.sh

This sets LISTEN_ADDR=0.0.0.0:8080 and runs the binary.

Windows

scripts\windows_run.cmd

Docker

bash scripts/docker_run.sh

Equivalent to:

docker run -it --rm -p 8080:8080 \
  -e LISTEN_ADDR=0.0.0.0:8080 \
  letstool/http2rdap:latest

Once running, the service is available at http://localhost:8080/.

Configuration

Each setting can be provided as a CLI flag or an environment variable. The CLI flag always takes priority. Resolution order: CLI flag → environment variable → default.

CLI flag	Environment variable	Default	Description
`-addr`	`LISTEN_ADDR`	`127.0.0.1:8080`	Address and port the HTTP server listens on.
`-rdap-timeout`	`RDAP_TIMEOUT`	`15s`	Per-query RDAP HTTP timeout. Accepts Go duration strings (e.g. `30s`).
`-request-timeout`	`REQUEST_TIMEOUT`	`20s`	Global HTTP request deadline.
`-temp-dir`	`TEMP_DIR`	`""` (OS default)	Directory for IANA bootstrap file cache. Empty string uses `os.TempDir()`.

Examples:

# Using CLI flags
./out/http2rdap -addr 0.0.0.0:9090 -rdap-timeout 30s -request-timeout 45s

# Using environment variables
LISTEN_ADDR=0.0.0.0:9090 RDAP_TIMEOUT=30s REQUEST_TIMEOUT=45s TEMP_DIR=/var/cache/rdap ./out/http2rdap

# Mixed: CLI flag overrides the environment variable for addr only
LISTEN_ADDR=0.0.0.0:9090 ./out/http2rdap -addr 127.0.0.1:8080

API Reference

`POST /api/v1/rdap`

Performs an RDAP lookup and returns parsed structured data. The authoritative RDAP server is discovered automatically via the IANA bootstrap registry (RFC 9224).

Exactly one of ip, domain, or asn must be provided per request.

Request body

{
  "domain": "example.com",
  "timeout": 10
}

Field	Type	Required	Description
`ip`	`string`	❌	IPv4 or IPv6 address to look up (e.g. `8.8.8.8`, `2001:4860:4860::8888`)
`domain`	`string`	❌	Domain name to look up (e.g. `example.com`)
`asn`	`string`	❌	Autonomous System Number, with or without the `AS` prefix (e.g. `15169` or `AS15169`)
`timeout`	`integer`	❌	Per-request RDAP timeout in seconds (`0` uses the server default).

Response body

{
  "status": "SUCCESS",
  "answers": {
    "query": "example.com",
    "queryType": "domain",
    "rdapServer": "https://rdap.verisign.com/com/v1/",
    "handle": "2336799_DOMAIN_COM-VRSN",
    "ldhName": "example.com",
    "unicodeName": "example.com",
    "status": ["active"],
    "nameServers": ["a.iana-servers.net", "b.iana-servers.net"],
    "delegationSigned": false,
    "created": "1995-08-14T04:00:00Z",
    "updated": "2026-01-16T18:26:50Z",
    "expires": "2026-08-13T04:00:00Z",
    "registrar": {
      "name": "RESERVED-Internet Assigned Numbers Authority",
      "url": "https://www.iana.org"
    },
    "selfLink": "https://rdap.verisign.com/com/v1/domain/EXAMPLE.COM"
  }
}

Field	Type	Description
`status`	`string`	`SUCCESS`, `NOTFOUND`, `ERROR`, or `RATELIMIT`
`answers`	`RDAPResult \| string`	Parsed RDAP result on success, or an error message string.

RDAPResult object:

Field	Type	Description
`query`	`string`	The original query value
`queryType`	`string`	`domain`, `ipv4`, `ipv6`, or `asn`
`rdapServer`	`string`	Authoritative RDAP server URL used for this query
`handle`	`string`	Registry object handle / identifier
`ldhName`	`string`	LDH domain name (domain lookups)
`unicodeName`	`string`	Internationalised domain name / IDN (domain lookups)
`status`	`string[]`	RDAP status codes (e.g. `active`, `inactive`)
`nameServers`	`string[]`	Authoritative name servers (domain lookups)
`delegationSigned`	`boolean`	DNSSEC delegation signing status (domain lookups)
`dnsKeyData`	`string`	DNSSEC key data, if present (domain lookups)
`startAddress`	`string`	First IP of the network block (IP lookups)
`endAddress`	`string`	Last IP of the network block (IP lookups)
`ipVersion`	`string`	`v4` or `v6` (IP lookups)
`cidrs`	`string[]`	CIDR notation(s) of the network block (IP lookups)
`startAutnum`	`integer`	First AS number in range (ASN lookups)
`endAutnum`	`integer`	Last AS number in range (ASN lookups)
`name`	`string`	Network or AS name
`type`	`string`	Allocation type or category
`country`	`string`	Two-letter country code
`created`	`date-time`	Registration / creation date
`updated`	`date-time`	Last update date
`expires`	`date-time`	Expiry date (domain lookups)
`registrar`	`Entity`	Sponsoring registrar
`registrant`	`Entity`	Registrant contact
`admin`	`Entity`	Administrative contact
`tech`	`Entity`	Technical contact
`abuse`	`Entity`	Abuse contact
`remarks`	`string[]`	Remarks and notices from the RDAP response
`selfLink`	`string`	Canonical RDAP URL for this object
`rawData`	`object`	Raw parsed RDAP JSON response

Each Entity object:

Field	Type	Description
`handle`	`string`	Registry handle
`roles`	`string[]`	Entity roles
`name`	`string`	Full name
`organization`	`string`	Organization
`email`	`string`	Email address
`phone`	`string`	Voice phone number
`fax`	`string`	Fax number
`street`	`string`	Street address
`city`	`string`	City
`state`	`string`	State or province
`postalCode`	`string`	Postal code
`country`	`string`	Country code
`url`	`string`	Website URL

Status codes

Value	HTTP	Meaning
`SUCCESS`	200	Query succeeded, `answers` contains the parsed RDAP result
`NOTFOUND`	200	No RDAP record found for the target
`ERROR`	200	Query failed (bad request, network error, or invalid input)
`RATELIMIT`	429	The authoritative RDAP server returned HTTP 429 — back off and retry later

Examples

Resolve a domain name:

curl -s -X POST http://localhost:8080/api/v1/rdap \
  -H "Content-Type: application/json" \
  -d '{"domain":"example.com"}' | jq .

{
  "status": "SUCCESS",
  "answers": {
    "query": "example.com",
    "queryType": "domain",
    "rdapServer": "https://rdap.verisign.com/com/v1/",
    "handle": "2336799_DOMAIN_COM-VRSN",
    "ldhName": "example.com",
    "status": ["active"],
    "nameServers": ["a.iana-servers.net", "b.iana-servers.net"],
    "delegationSigned": false,
    "created": "1995-08-14T04:00:00Z",
    "expires": "2026-08-13T04:00:00Z",
    "selfLink": "https://rdap.verisign.com/com/v1/domain/EXAMPLE.COM"
  }
}

Look up an IP address:

curl -s -X POST http://localhost:8080/api/v1/rdap \
  -H "Content-Type: application/json" \
  -d '{"ip":"8.8.8.8"}' | jq .

{
  "status": "SUCCESS",
  "answers": {
    "query": "8.8.8.8",
    "queryType": "ip",
    "rdapServer": "https://rdap.arin.net/registry/",
    "handle": "NET-8-8-8-0-2",
    "startAddress": "8.8.8.0",
    "endAddress": "8.8.8.255",
    "ipVersion": "v4",
    "cidrs": ["8.8.8.0/24"],
    "name": "GOGL",
    "type": "DIRECT ALLOCATION",
    "country": "US"
  }
}

Look up an AS number:

curl -s -X POST http://localhost:8080/api/v1/rdap \
  -H "Content-Type: application/json" \
  -d '{"asn":"AS15169"}' | jq .

{
  "status": "SUCCESS",
  "answers": {
    "query": "AS15169",
    "queryType": "asn",
    "rdapServer": "https://rdap.arin.net/registry/",
    "handle": "AS15169",
    "startAutnum": 15169,
    "endAutnum": 15169,
    "name": "GOOGLE"
  }
}

`GET /`

Returns the embedded interactive web UI.

`GET /openapi.json`

Returns the full OpenAPI 3.0 specification of the API.

`GET /favicon.png`

Returns the application icon.

Development

Dependencies are managed with Go modules and vendored in the vendor/ directory. After cloning:

bash scripts/000_init.sh
go build ./...

The test suite and initialization scripts are located in scripts/:

scripts/000_init.sh     # go mod tidy && go mod vendor
scripts/999_test.sh     # Integration tests (server must be running)

AI-Assisted Development

This project was developed with the assistance of Claude Sonnet 4.6 by Anthropic.

Migrated from http2whois (WHOIS-over-HTTP) to http2rdap (RDAP-over-HTTP) by Claude Sonnet 4.6 by Anthropic.

Name		Name	Last commit message	Last commit date
Latest commit History 2 Commits
.github/workflows		.github/workflows
api		api
build		build
cmd/http2rdap		cmd/http2rdap
docs		docs
internal/rdapclient		internal/rdapclient
scripts		scripts
.dockerignore		.dockerignore
.gitignore		.gitignore
CLAUDE.md		CLAUDE.md
LICENSE		LICENSE
README.md		README.md
go.mod		go.mod
go.sum		go.sum

Project	GitHub	Docker Hub	Description
`http2dns`	letstool/http2dns	letstool/http2dns	Fast & lightweight HTTP gateway that serves DNS queries as a JSON REST API
`http2whois`	letstool/http2whois	letstool/http2whois	Fast & lightweight HTTP gateway that serves WHOIS queries as a JSON REST API
`http2rdap`	letstool/http2rdap	letstool/http2rdap	Fast & lightweight HTTP gateway that serves RDAP queries as a JSON REST API
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API Reference

`POST /api/v1/rdap`

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Response body

Status codes

Examples

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`GET /openapi.json`

`GET /favicon.png`

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API Reference

POST /api/v1/rdap

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GET /favicon.png

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`POST /api/v1/rdap`

`GET /`

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