# Certificate Transparency Subdomain Search (crt.sh alternative) (`advx/ct-domain-lookup`) Actor Find subdomains and TLS certificates for any domain from Certificate Transparency logs. A fast, working crt.sh alternative for subdomain enumeration, recon and attack-surface mapping. Returns unique hostnames with first/last seen and issuers, or raw certificates. - **URL**: https://apify.com/advx/ct-domain-lookup.md - **Developed by:** [Sevastian Z](https://apify.com/advx) (community) - **Categories:** Developer tools, Automation - **Stats:** 1 total users, 0 monthly users, 100.0% runs succeeded, NaN bookmarks - **User rating**: No ratings yet ## Pricing Pay per usage This Actor is paid per platform usage. The Actor is free to use, and you only pay for the Apify platform usage, which gets cheaper the higher subscription plan you have. Learn more: https://docs.apify.com/platform/actors/running/actors-in-store#pay-per-usage ## What's an Apify Actor? Actors are a software tools running on the Apify platform, for all kinds of web data extraction and automation use cases. In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours, and optionally produces a well-defined JSON output, datasets with results, or files in key-value store. In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server. Actors are written with capital "A". ## How to integrate an Actor? If asked about integration, you help developers integrate Actors into their projects. You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready. The best way to integrate Actors is as follows. In JavaScript/TypeScript projects, use official [JavaScript/TypeScript client](https://docs.apify.com/api/client/js.md): ```bash npm install apify-client ``` In Python projects, use official [Python client library](https://docs.apify.com/api/client/python.md): ```bash pip install apify-client ``` In shell scripts, use [Apify CLI](https://docs.apify.com/cli/docs.md): ````bash # MacOS / Linux curl -fsSL https://apify.com/install-cli.sh | bash # Windows irm https://apify.com/install-cli.ps1 | iex ```bash In AI frameworks, you might use the [Apify MCP server](https://docs.apify.com/platform/integrations/mcp.md). If your project is in a different language, use the [REST API](https://docs.apify.com/api/v2.md). For usage examples, see the [API](#api) section below. For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt). # README ## Certificate Transparency Subdomain Search (crt.sh alternative) Find every subdomain and TLS certificate issued for a domain, straight from public Certificate Transparency logs. A fast, working alternative to crt.sh for subdomain enumeration, recon, attack-surface mapping and asset discovery. Every publicly trusted certificate is logged in Certificate Transparency. That makes CT logs one of the best sources for discovering the hostnames an organization actually uses, including forgotten staging, dev and internal subdomains. ### What it does - Queries CT logs for a domain (and optionally its subdomains). - Returns either: - **Unique hostnames** (default): one row per hostname, deduplicated, with how many certificates referenced it, first/last seen dates and issuers. Ideal for subdomain enumeration. - **Raw certificates**: one row per certificate, with all SAN names, issuer and validity window. - Wildcard certificates (`*.example.com`) are flagged. ### Input | Field | Type | Description | |-------|------|-------------| | `domain` | string, required | Domain to search, e.g. `example.com` | | `includeSubdomains` | boolean | Also include certificates issued for subdomains (default `true`) | | `output` | `names` \| `certificates` | Aggregate to unique hostnames, or return raw certificates (default `names`) | ```json { "domain": "example.com", "includeSubdomains": true, "output": "names" } ```` ### Output (names mode) | Field | Description | |-------|-------------| | `name` | discovered hostname | | `wildcard` | a wildcard certificate covered this name | | `cert_count` | how many certificates referenced it | | `first_seen` / `last_seen` | earliest / latest certificate `not_before` | | `issuers` | certificate authorities that issued for it | ### Use cases - Subdomain enumeration for recon and bug bounty. - Attack-surface and asset discovery for security teams. - Monitoring which CAs issue certificates for your domains. ### Related: catch domains impersonating you CT search finds certificates for *your* domain. Attackers register **lookalike and typosquatted domains** and get their own certificates to phish your users. To detect those, scan with [Lookalike / Typosquat Domain Scan](https://apify.com/advx/lookalert-domain-scan) — it generates lookalike permutations, verifies registration via DNS and RDAP, and scores phishing risk. ### Notes Data comes from public Certificate Transparency logs via the Cert Spotter API. The free tier is rate-limited; if you hit a rate limit, retry in a minute. # Actor input Schema ## `domain` (type: `string`): Domain to search Certificate Transparency logs for, e.g. example.com ## `includeSubdomains` (type: `boolean`): Also return certificates issued for subdomains of the domain ## `output` (type: `string`): names = one row per unique hostname (subdomain enumeration); certificates = one row per certificate ## Actor input object example ```json { "domain": "example.com", "includeSubdomains": true, "output": "names" } ``` # API You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup. ## JavaScript example ```javascript import { ApifyClient } from 'apify-client'; // Initialize the ApifyClient with your Apify API token // Replace the '' with your token const client = new ApifyClient({ token: '', }); // Prepare Actor input const input = {}; // Run the Actor and wait for it to finish const run = await client.actor("advx/ct-domain-lookup").call(input); // Fetch and print Actor results from the run's dataset (if any) console.log('Results from dataset'); console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`); const { items } = await client.dataset(run.defaultDatasetId).listItems(); items.forEach((item) => { console.dir(item); }); // 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs ``` ## Python example ```python from apify_client import ApifyClient # Initialize the ApifyClient with your Apify API token # Replace '' with your token. client = ApifyClient("") # Prepare the Actor input run_input = {} # Run the Actor and wait for it to finish run = client.actor("advx/ct-domain-lookup").call(run_input=run_input) # Fetch and print Actor results from the run's dataset (if there are any) print("💾 Check your data here: https://console.apify.com/storage/datasets/" + run["defaultDatasetId"]) for item in client.dataset(run["defaultDatasetId"]).iterate_items(): print(item) # 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start ``` ## CLI example ```bash echo '{}' | apify call advx/ct-domain-lookup --silent --output-dataset ``` ## MCP server setup ```json { "mcpServers": { "apify": { "command": "npx", "args": [ "mcp-remote", "https://mcp.apify.com/?tools=advx/ct-domain-lookup", "--header", "Authorization: Bearer " ] } } } ``` ## OpenAPI specification ```json { "openapi": "3.0.1", "info": { "title": "Certificate Transparency Subdomain Search (crt.sh alternative)", "description": "Find subdomains and TLS certificates for any domain from Certificate Transparency logs. A fast, working crt.sh alternative for subdomain enumeration, recon and attack-surface mapping. Returns unique hostnames with first/last seen and issuers, or raw certificates.", "version": "0.1", "x-build-id": "oI15qMfSkLiyqh2oK" }, "servers": [ { "url": "https://api.apify.com/v2" } ], "paths": { "/acts/advx~ct-domain-lookup/run-sync-get-dataset-items": { "post": { "operationId": "run-sync-get-dataset-items-advx-ct-domain-lookup", "x-openai-isConsequential": false, "summary": "Executes an Actor, waits for its completion, and returns Actor's dataset items in response.", "tags": [ "Run Actor" ], "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/inputSchema" } } } }, "parameters": [ { "name": "token", "in": "query", "required": true, "schema": { "type": "string" }, "description": "Enter your Apify token here" } ], "responses": { "200": { "description": "OK" } } } }, "/acts/advx~ct-domain-lookup/runs": { "post": { "operationId": "runs-sync-advx-ct-domain-lookup", "x-openai-isConsequential": false, "summary": "Executes an Actor and returns information about the initiated run in response.", "tags": [ "Run Actor" ], "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/inputSchema" } } } }, "parameters": [ { "name": "token", "in": "query", "required": true, "schema": { "type": "string" }, "description": "Enter your Apify token here" } ], "responses": { "200": { "description": "OK", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/runsResponseSchema" } } } } } } }, "/acts/advx~ct-domain-lookup/run-sync": { "post": { "operationId": "run-sync-advx-ct-domain-lookup", "x-openai-isConsequential": false, "summary": "Executes an Actor, waits for completion, and returns the OUTPUT from Key-value store in response.", "tags": [ "Run Actor" ], "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/inputSchema" } } } }, "parameters": [ { "name": "token", "in": "query", "required": true, "schema": { "type": "string" }, "description": "Enter your Apify token here" } ], "responses": { "200": { "description": "OK" } } } } }, "components": { "schemas": { "inputSchema": { "type": "object", "required": [ "domain" ], "properties": { "domain": { "title": "Domain", "type": "string", "description": "Domain to search Certificate Transparency logs for, e.g. example.com" }, "includeSubdomains": { "title": "Include subdomains", "type": "boolean", "description": "Also return certificates issued for subdomains of the domain", "default": true }, "output": { "title": "Output mode", "enum": [ "names", "certificates" ], "type": "string", "description": "names = one row per unique hostname (subdomain enumeration); certificates = one row per certificate", "default": "names" } } }, "runsResponseSchema": { "type": "object", "properties": { "data": { "type": "object", "properties": { "id": { "type": "string" }, "actId": { "type": "string" }, "userId": { "type": "string" }, "startedAt": { "type": "string", "format": "date-time", "example": "2025-01-08T00:00:00.000Z" }, "finishedAt": { "type": "string", "format": "date-time", "example": "2025-01-08T00:00:00.000Z" }, "status": { "type": "string", "example": "READY" }, "meta": { "type": "object", "properties": { "origin": { "type": "string", "example": "API" }, "userAgent": { "type": "string" } } }, "stats": { "type": "object", "properties": { "inputBodyLen": { "type": "integer", "example": 2000 }, "rebootCount": { "type": "integer", "example": 0 }, "restartCount": { "type": "integer", "example": 0 }, "resurrectCount": { "type": "integer", "example": 0 }, "computeUnits": { "type": "integer", "example": 0 } } }, "options": { "type": "object", "properties": { "build": { "type": "string", "example": "latest" }, "timeoutSecs": { "type": "integer", "example": 300 }, "memoryMbytes": { "type": "integer", "example": 1024 }, "diskMbytes": { "type": "integer", "example": 2048 } } }, "buildId": { "type": "string" }, "defaultKeyValueStoreId": { "type": "string" }, "defaultDatasetId": { "type": "string" }, "defaultRequestQueueId": { "type": "string" }, "buildNumber": { "type": "string", "example": "1.0.0" }, "containerUrl": { "type": "string" }, "usage": { "type": "object", "properties": { "ACTOR_COMPUTE_UNITS": { "type": "integer", "example": 0 }, "DATASET_READS": { "type": "integer", "example": 0 }, "DATASET_WRITES": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_READS": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_WRITES": { "type": "integer", "example": 1 }, "KEY_VALUE_STORE_LISTS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_READS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_WRITES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_INTERNAL_GBYTES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_EXTERNAL_GBYTES": { "type": "integer", "example": 0 }, "PROXY_RESIDENTIAL_TRANSFER_GBYTES": { "type": "integer", "example": 0 }, "PROXY_SERPS": { "type": "integer", "example": 0 } } }, "usageTotalUsd": { "type": "number", "example": 0.00005 }, "usageUsd": { "type": "object", "properties": { "ACTOR_COMPUTE_UNITS": { "type": "integer", "example": 0 }, "DATASET_READS": { "type": "integer", "example": 0 }, "DATASET_WRITES": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_READS": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_WRITES": { "type": "number", "example": 0.00005 }, "KEY_VALUE_STORE_LISTS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_READS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_WRITES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_INTERNAL_GBYTES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_EXTERNAL_GBYTES": { "type": "integer", "example": 0 }, "PROXY_RESIDENTIAL_TRANSFER_GBYTES": { "type": "integer", "example": 0 }, "PROXY_SERPS": { "type": "integer", "example": 0 } } } } } } } } } } ```