diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ace168..74acfc9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+
+## [2.4.1-beta-1] - 2026-06-26
+
+### Fixed
+- Resolve external `$ref` (HTTP/HTTPS URLs) instead of crashing with `TypeError`. External schemas are fetched, cached, and inlined at parse time using Node's built-in `http`/`https` modules.
+
+
 ## [2.4.0] - 2026-05-07
 
 ### Added
diff --git a/index.js b/index.js
index a378f2a..203cf6c 100644
--- a/index.js
+++ b/index.js
@@ -66,12 +66,13 @@ try {
 	require('./src/utils/error.js')('use argv: -c/--configuration. configuration file path does not exist or is not correct: ' + argv.configuration);
 }
 
+;(async () => {
 global.definition = require('./src/parser/definition.js')()
 const version = require('./src/parser/version.js')()
 global.environmentVariables = {}
 global.testParams = {}
 global.configurationFile = configurationFile
-require('./src/parser/'+version+'/refs.js')()
+await require('./src/parser/'+version+'/refs.js')()
 
 const schemaHostBasePath = require('./src/parser/'+version+'/schemaHostBasePath.js')()
 const endpointsParsed = require('./src/parser/endpoints.js')()
@@ -231,8 +232,8 @@ _.forEach(environments, function (element) {
 	}
 	if ( element.custom_authorizations_file ) {
 		require('./src/parser/authorizationRequests.js')(endpointsStage,element.custom_authorizations_file)
-	} else if(global.definition.components.securitySchemes){
-		let securityDefinition = require('./src/parser/openapiAuthorizationDefinition.js')(global.definition.components.securitySchemes)
+	} else if(globalThis.definition.components?.securitySchemes){
+		let securityDefinition = require('./src/parser/openapiAuthorizationDefinition.js')(globalThis.definition.components.securitySchemes)
 		if(securityDefinition){
 			require('./src/parser/authorizationRequests.js')(endpointsStage,null,securityDefinition)
 		} 
@@ -299,10 +300,13 @@ function addLettersToName(collection) {
 				// Añade una letra al nombre de cada Test Case, justo despues del status code. Ej.: 200a OK
 				// Controla el exceso de Test Cases y añade dos letras en caso de ser necesario. Ej.: 200aa OK, 200ab OK
 				for (let k in array) {
-					array[k].name = _.replace(array[k].name, array[k].aux.status, 
+					array[k].name = _.replace(array[k].name, array[k].aux.status,
 						k < alphabet.length ? array[k].aux.status + alphabet[k] : array[k].aux.status + alphabet[Math.floor(k / alphabet.length) - 1] + alphabet[k % alphabet.length]);
 				}
 			}
 		}
 	}
-}
\ No newline at end of file
+}
+})().catch(err => {
+	require('./src/utils/error.js')(err.message || String(err))
+})
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index 4cd3e68..e8dffa3 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "openapi2postman",
-  "version": "2.4.0",
+  "version": "2.4.1-beta-1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "openapi2postman",
-      "version": "2.4.0",
+      "version": "2.4.1-beta-1",
       "license": "ISC",
       "dependencies": {
         "js-yaml": "^4.1.0",
diff --git a/package.json b/package.json
index 1ccfcf3..0b05d30 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "openapi2postman",
-  "version": "2.4.0",
+  "version": "2.4.1-beta-1",
   "description": "openapi2postman",
   "bin": {
     "o2p": "index.js"
diff --git a/seeds/parserInitialGoodOpenApi3.json b/seeds/parserInitialGoodOpenApi3.json
index 6e46152..999350d 100644
--- a/seeds/parserInitialGoodOpenApi3.json
+++ b/seeds/parserInitialGoodOpenApi3.json
@@ -9,7 +9,7 @@
     },
     "servers":[
        {
-          "url":"http://petstore.swagger.io/v1"
+          "url":"https://petstore.swagger.io/v1"
        }
     ],
     "paths":{
diff --git a/src/parser/openapi3/refs.js b/src/parser/openapi3/refs.js
index 26ecd3d..6daa70e 100644
--- a/src/parser/openapi3/refs.js
+++ b/src/parser/openapi3/refs.js
@@ -2,36 +2,18 @@
 
 'use strict'
 
-function eachRecursive(obj) {
-	for (let k in obj) {
-		if (typeof obj[k] == "object" && obj[k] !== null) {
-			eachRecursive(obj[k]);
-		} else if (k == '$ref') {
-			const siblings = {}
-			for (const sib of Object.keys(obj)) {
-				if (sib !== '$ref') {
-					siblings[sib] = obj[sib]
-				}
-			}
-			let property = obj[k]
-			property = property.replace('#/', '')
-			let propertiesArray = property.split('/')
-			let refObject = findObject(globalThis.definition, propertiesArray)
-			delete obj[k]
-			Object.assign(obj, refObject, siblings)
-		}
-	}
-}
+const createRefsModule = require('../refs')
 
-function findObject(obj, propertiesArray) {
-	if(propertiesArray.length < 1) {
-		return obj
+function collectSiblings(obj) {
+	const siblings = {}
+	for (const sib of Object.keys(obj)) {
+		if (sib !== '$ref') siblings[sib] = obj[sib]
 	}
-
-	let property = propertiesArray.shift()
-	return findObject(obj[property], propertiesArray)
+	return siblings
 }
 
+const resolveRefs = createRefsModule({ prepareSiblings: collectSiblings })
+
 function liftAdditionalOperations() {
 	if (!globalThis.definition.paths) return
 	for (const path in globalThis.definition.paths) {
@@ -46,9 +28,9 @@ function liftAdditionalOperations() {
 }
 
 module.exports = function() {
-	return function get() {
-		eachRecursive(globalThis.definition)
+	return async function get() {
+		await resolveRefs(globalThis.definition, globalThis.definition)
 		liftAdditionalOperations()
 		return globalThis.definition
 	}
-}()
\ No newline at end of file
+}()
diff --git a/src/parser/refs.js b/src/parser/refs.js
new file mode 100644
index 0000000..2105501
--- /dev/null
+++ b/src/parser/refs.js
@@ -0,0 +1,103 @@
+/** Part of APIAddicts. See LICENSE fileor full copyright and licensing details. Supported by Madrid Digital and CloudAPPi **/
+
+'use strict'
+
+const https = require('node:https')
+const http = require('node:http')
+const yaml = require('js-yaml')
+const error = require('../utils/error')
+
+function parseYamlResponse(data, url, resolve, reject) {
+	try { resolve(yaml.load(data)) }
+	catch (e) { reject(new Error('Failed to parse external ref from ' + url + ': ' + e.message)) }
+}
+
+function fetchUrl(url) {
+	return new Promise((resolve, reject) => {
+		const client = url.startsWith('https://') ? https : http
+		client.get(url, (res) => {
+			if (res.statusCode >= 300 && res.statusCode < 400 && res.headers.location) {
+				return fetchUrl(res.headers.location).then(resolve, reject)
+			}
+			if (res.statusCode < 200 || res.statusCode >= 300) {
+				res.resume()
+				return reject(new Error('Failed to fetch external ref ' + url + ': HTTP ' + res.statusCode))
+			}
+			let data = ''
+			res.on('data', chunk => data += chunk)
+			res.on('end', () => parseYamlResponse(data, url, resolve, reject))
+		}).on('error', e => reject(new Error('Failed to fetch external ref ' + url + ': ' + e.message)))
+	})
+}
+
+function extractFragment(refValue) {
+	const hashIdx = refValue.indexOf('#')
+	return {
+		baseUrl: hashIdx >= 0 ? refValue.substring(0, hashIdx) : refValue,
+		fragment: hashIdx >= 0 ? refValue.substring(hashIdx + 1) : ''
+	}
+}
+
+function findObject(obj, propertiesArray) {
+	if (propertiesArray.length < 1) return obj
+	if (obj === undefined || obj === null) return undefined
+	const property = propertiesArray.shift()
+	return findObject(obj[property], propertiesArray)
+}
+
+function isExternalRef(refValue) {
+	return refValue.startsWith('http://') || refValue.startsWith('https://')
+}
+
+function resolveInternalRef(refValue, localDefinition) {
+	const fragment = refValue.replace(/^#\/?/, '')
+	const parts = fragment ? fragment.split('/') : []
+	const refObject = parts.length ? findObject(localDefinition, [...parts]) : localDefinition
+	if (refObject === undefined) { error('$ref not found: ' + refValue) }
+	return refObject
+}
+
+module.exports = function createRefsModule(opts) {
+	const prepareSiblings = opts?.prepareSiblings || function() { return {} }
+	const externalDocCache = new Map()
+
+	async function ensureFetched(baseUrl, seenUrls) {
+		if (externalDocCache.has(baseUrl)) return
+		if (seenUrls.has(baseUrl)) { error('Circular external $ref detected: ' + baseUrl) }
+		const childSeen = new Set(seenUrls)
+		childSeen.add(baseUrl)
+		let doc
+		try { doc = await fetchUrl(baseUrl) }
+		catch (e) { error(e.message) }
+		await resolveRefs(doc, doc, childSeen)
+		externalDocCache.set(baseUrl, doc)
+	}
+
+	async function fetchAndResolveExternal(refValue, seenUrls) {
+		const { baseUrl, fragment } = extractFragment(refValue)
+		await ensureFetched(baseUrl, seenUrls)
+		const doc = externalDocCache.get(baseUrl)
+		if (!fragment || fragment === '/') return doc
+		const parts = fragment.replace(/^\//, '').split('/')
+		const resolved = findObject(doc, parts)
+		if (resolved === undefined) { error('External $ref fragment not found: ' + fragment + ' in ' + baseUrl) }
+		return resolved
+	}
+
+	async function resolveRefs(obj, localDefinition, seenUrls = new Set()) {
+		for (const k in obj) {
+			if (typeof obj[k] === 'object' && obj[k] !== null) {
+				await resolveRefs(obj[k], localDefinition, seenUrls)
+			} else if (k === '$ref') {
+				const siblings = prepareSiblings(obj)
+				const refObject = isExternalRef(obj[k])
+					? await fetchAndResolveExternal(obj[k], seenUrls)
+					: resolveInternalRef(obj[k], localDefinition)
+				delete obj[k]
+				Object.assign(obj, refObject, siblings)
+			}
+		}
+	}
+
+	return resolveRefs
+}
diff --git a/src/parser/swagger2/refs.js b/src/parser/swagger2/refs.js
index 6654c80..d9ed935 100644
--- a/src/parser/swagger2/refs.js
+++ b/src/parser/swagger2/refs.js
@@ -2,39 +2,13 @@
 
 'use strict'
 
-function eachRecursive(obj) {
-    for (var k in obj) {
-		if (typeof obj[k] == "object" && obj[k] !== null) {
-			eachRecursive(obj[k]);
-		} else {
-			if(k == '$ref') {
-				let property = obj[k]
-				property = property.replace('#/', '')
-				let propertiesArray = property.split('/')
-				let refObject = findObject(global.definition, propertiesArray)
+const createRefsModule = require('../refs')
 
-				// Clear ref property
-				delete obj[k]
-
-				// Assign properties refOcject
-				Object.assign(obj, refObject)
-			}
-		}
-	}
-}
-
-function findObject(obj, propertiesArray) {
-	if(propertiesArray.length < 1) {
-		return obj
-	}
-
-	let property = propertiesArray.shift()
-	return findObject(obj[property], propertiesArray)
-}
+const resolveRefs = createRefsModule()
 
 module.exports = function() {
-	return function get() {
-		eachRecursive(global.definition)
-		return global.definition
+	return async function get() {
+		await resolveRefs(globalThis.definition, globalThis.definition)
+		return globalThis.definition
 	}
-}()
\ No newline at end of file
+}()
diff --git a/test/parser-refs.js b/test/parser-refs.js
new file mode 100644
index 0000000..abbc43d
--- /dev/null
+++ b/test/parser-refs.js
@@ -0,0 +1,252 @@
+/** Part of APIAddicts. See LICENSE fileor full copyright and licensing details. Supported by Madrid Digital and CloudAPPi **/
+
+const assert = require('node:assert')
+const http = require('node:http')
+
+const FLAT_SCHEMA_YAML = [
+	'components:',
+	'  schemas:',
+	'    Pet:',
+	'      type: object',
+	'      properties:',
+	'        name:',
+	'          type: string',
+].join('\n')
+
+const NESTED_SCHEMA_YAML = [
+	'components:',
+	'  schemas:',
+	'    Pet:',
+	'      type: object',
+	'      properties:',
+	'        address:',
+	"          $ref: '#/components/schemas/Address'",
+	'    Address:',
+	'      type: object',
+	'      properties:',
+	'        street:',
+	'          type: string',
+].join('\n')
+
+const PET_SCHEMA = { type: 'object', properties: { name: { type: 'string' } } }
+
+const PET_WITH_ADDRESS = {
+	type: 'object',
+	properties: {
+		address: { type: 'object', properties: { street: { type: 'string' } } }
+	}
+}
+
+function startServer(responseBody) {
+	return new Promise(resolve => {
+		const server = http.createServer((req, res) => {
+			res.writeHead(200, { 'Content-Type': 'application/yaml' })
+			res.end(responseBody)
+		})
+		server.listen(0, '127.0.0.1', () => resolve(server))
+	})
+}
+
+describe('parser-refs', () => {
+	beforeEach(() => {
+		delete require.cache[require.resolve('../src/parser/openapi3/refs.js')]
+		delete require.cache[require.resolve('../src/parser/swagger2/refs.js')]
+	})
+
+	it('resolves external http $ref with fragment (openapi3)', async () => {
+		const server = await startServer(FLAT_SCHEMA_YAML)
+		const { port } = server.address()
+
+		globalThis.definition = {
+			paths: {
+				'/pets': {
+					get: {
+						responses: {
+							'200': {
+								content: {
+									'application/json': {
+										schema: { '$ref': `http://127.0.0.1:${port}/schema.yaml#/components/schemas/Pet` }
+									}
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+
+		const refs = require('../src/parser/openapi3/refs.js')
+		await refs()
+		server.close()
+
+		const schema = globalThis.definition.paths['/pets'].get.responses['200'].content['application/json'].schema
+		assert.deepStrictEqual(schema, PET_SCHEMA)
+	})
+
+	it('resolves external http $ref with fragment (swagger2)', async () => {
+		const server = await startServer(FLAT_SCHEMA_YAML)
+		const { port } = server.address()
+
+		globalThis.definition = {
+			paths: {
+				'/pets': {
+					get: {
+						responses: {
+							'200': {
+								schema: { '$ref': `http://127.0.0.1:${port}/schema.yaml#/components/schemas/Pet` }
+							}
+						}
+					}
+				}
+			}
+		}
+
+		const refs = require('../src/parser/swagger2/refs.js')
+		await refs()
+		server.close()
+
+		const schema = globalThis.definition.paths['/pets'].get.responses['200'].schema
+		assert.deepStrictEqual(schema, PET_SCHEMA)
+	})
+
+	it('resolves nested internal $refs inside external document (openapi3)', async () => {
+		const server = await startServer(NESTED_SCHEMA_YAML)
+		const { port } = server.address()
+
+		globalThis.definition = {
+			paths: {
+				'/pets': {
+					get: {
+						responses: {
+							'200': {
+								content: {
+									'application/json': {
+										schema: { '$ref': `http://127.0.0.1:${port}/schema.yaml#/components/schemas/Pet` }
+									}
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+
+		const refs = require('../src/parser/openapi3/refs.js')
+		await refs()
+		server.close()
+
+		const schema = globalThis.definition.paths['/pets'].get.responses['200'].content['application/json'].schema
+		assert.deepStrictEqual(schema, PET_WITH_ADDRESS)
+	})
+
+	it('resolves transitive external $refs (openapi3)', async () => {
+		const addressServer = await startServer([
+			'type: object',
+			'properties:',
+			'  street:',
+			'    type: string',
+		].join('\n'))
+		const { port: addressPort } = addressServer.address()
+
+		const petServer = await startServer([
+			'components:',
+			'  schemas:',
+			'    Pet:',
+			'      type: object',
+			'      properties:',
+			'        address:',
+			`          $ref: 'http://127.0.0.1:${addressPort}/address.yaml'`,
+		].join('\n'))
+		const { port: petPort } = petServer.address()
+
+		globalThis.definition = {
+			paths: {
+				'/pets': {
+					get: {
+						responses: {
+							'200': {
+								content: {
+									'application/json': {
+										schema: { '$ref': `http://127.0.0.1:${petPort}/pet.yaml#/components/schemas/Pet` }
+									}
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+
+		const refs = require('../src/parser/openapi3/refs.js')
+		await refs()
+		petServer.close()
+		addressServer.close()
+
+		const schema = globalThis.definition.paths['/pets'].get.responses['200'].content['application/json'].schema
+		assert.deepStrictEqual(schema, PET_WITH_ADDRESS)
+	})
+
+	it('emits clear error for HTTP error response on external $ref (openapi3)', async () => {
+		const server = http.createServer((req, res) => {
+			res.writeHead(404)
+			res.end('Not Found')
+		})
+		await new Promise(resolve => server.listen(0, '127.0.0.1', resolve))
+		const { port } = server.address()
+
+		globalThis.definition = {
+			paths: {
+				'/pets': {
+					get: { responses: { '200': { schema: { '$ref': `http://127.0.0.1:${port}/schema.yaml` } } } }
+				}
+			}
+		}
+
+		const originalExit = process.exit
+		const originalError = console.error
+		let exitCode
+		process.exit = (code) => { exitCode = code; throw new Error('process.exit:' + code) }
+		console.error = () => {}
+
+		const refs = require('../src/parser/openapi3/refs.js')
+		try {
+			await refs()
+			assert.fail('Expected process.exit to be called')
+		} catch (e) {
+			if (exitCode === undefined) throw e
+			assert.strictEqual(exitCode, 1)
+		} finally {
+			process.exit = originalExit
+			console.error = originalError
+			server.close()
+		}
+	})
+
+	it('emits clear error for unreachable external $ref (openapi3)', async () => {
+		globalThis.definition = {
+			paths: {
+				'/pets': {
+					get: { responses: { '200': { schema: { '$ref': 'http://127.0.0.1:1/schema.yaml' } } } }
+				}
+			}
+		}
+
+		const originalExit = process.exit
+		const originalError = console.error
+		let exitCode
+		process.exit = (code) => { exitCode = code; throw new Error('process.exit:' + code) }
+		console.error = () => {}
+
+		const refs = require('../src/parser/openapi3/refs.js')
+		try {
+			await refs()
+			assert.fail('Expected process.exit to be called')
+		} catch (e) {
+			if (exitCode === undefined) throw e
+			assert.strictEqual(exitCode, 1)
+		} finally {
+			process.exit = originalExit
+			console.error = originalError
+		}
+	})
+})