diff --git a/app/lib/server/index.js b/app/lib/server/index.js
index 2ca58a15f606b..c4dc9e428fabd 100644
--- a/app/lib/server/index.js
+++ b/app/lib/server/index.js
@@ -21,6 +21,7 @@ import './oauth/facebook';
 import './oauth/google';
 import './oauth/proxy';
 import './oauth/twitter';
+import './oauth/custom';
 import './methods/addOAuthService';
 import './methods/addUsersToRoom';
 import './methods/addUserToRoom';
diff --git a/app/lib/server/oauth/custom.js b/app/lib/server/oauth/custom.js
new file mode 100644
index 0000000000000..e326d31cf5c79
--- /dev/null
+++ b/app/lib/server/oauth/custom.js
@@ -0,0 +1,110 @@
+import { Match, check } from 'meteor/check';
+import _ from 'underscore';
+import { HTTP } from 'meteor/http';
+import { ServiceConfiguration } from 'meteor/service-configuration';
+import { OAuth } from 'meteor/oauth';
+import { registerAccessTokenService } from './oauth';
+
+function getIdentity(accessToken, config) {
+	try {
+		return HTTP.get(
+			config.serverURL + config.identityPath,
+			{
+				headers: {
+					Authorization: `Bearer ${ accessToken }`,
+					Accept: 'application/json',
+				},
+			}).data;
+	} catch (err) {
+		throw _.extend(new Error(`Failed to fetch identity from custom OAuth ${ config.service }. ${ err.message }`), { response: err.response });
+	}
+}
+
+// use RFC7662 OAuth 2.0 Token Introspection
+function getTokeninfo(idToken, config) {
+	try {
+		const introspectPath = '/introspect';	// not yet configurable in Rocket.Chat, thought RFC defines that path
+		return HTTP.post(
+			config.serverURL + introspectPath,
+			{
+				auth: `${ config.clientId }:${ OAuth.openSecret(config.secret) }`,
+				headers: {
+					Accept: 'application/json',
+				},
+				params: {
+					token: idToken,
+					token_type_hint: 'access_token',
+				},
+			}).data;
+	} catch (err) {
+		throw _.extend(new Error(`Failed to fetch tokeninfo from custom OAuth ${ config.service }. ${ err.message }`), { response: err.response });
+	}
+}
+
+registerAccessTokenService('custom', function(options) {
+	check(options, Match.ObjectIncluding({
+		accessToken: String,
+		expiresIn: Match.Maybe(Match.Integer),
+		scope: Match.Maybe(String),
+		identity: Match.Maybe(Object),
+	}));
+
+	const config = ServiceConfiguration.configurations.findOne({ service: options.serviceName });
+	let tokeninfo;
+	if (!options.expiresIn || !options.scope) {
+		try {
+			tokeninfo = getTokeninfo(options.accessToken, config);
+			// console.log('app/lib/server/oauth/custom.js: tokeninfo=', tokeninfo);
+		} catch (err) {
+			// ignore tokeninfo failures, as getIdentity still validates the token, we just dont know how long it's valid
+			console.log(err);
+		}
+	}
+	const identity = options.identity || getIdentity(options.accessToken, config);
+
+	// support OpenID Connect /userinfo names
+	if (typeof identity.profile_image_url === 'undefined' && identity.picture) {
+		identity.profile_image_url = identity.picture;
+	}
+	if (typeof identity.lang === 'undefined' && identity.locale) {
+		identity.profile_image_url = identity.picture;
+	}
+
+	const serviceData = {
+		_OAuthCustom: true,
+		accessToken: options.accessToken,
+		expiresAt: tokeninfo.exp || (+new Date) + (1000 * parseInt(options.expiresIn, 10)),
+		scope: options.scope || tokeninfo.scope || config.scope.split(/ /),
+		id: identity[config.usernameField],
+	};
+
+	// only set the token in serviceData if it's there. this ensures
+	// that we don't lose old ones (since we only get this on the first
+	// log in attempt)
+	if (options.refreshToken) {
+		serviceData.refreshToken = options.refreshToken;
+	}
+
+	const whitelistedFields = [
+		'name',
+		'description',
+		'profile_image_url',
+		'profile_image_url_https',
+		'lang',
+		'email',
+	];
+	if (!whitelistedFields.includes(config.usernameField) && typeof serviceData[config.usernameField] === 'undefined') {
+		whitelistedFields.push(config.usernameField);
+	}
+	const fields = _.pick(identity, whitelistedFields);
+	_.extend(serviceData, fields);
+
+	return {
+		serviceData,
+		options: {
+			profile: {
+				name: identity.name,
+			},
+		},
+	};
+});
diff --git a/app/lib/server/oauth/oauth.js b/app/lib/server/oauth/oauth.js
index c735ff0cc5b33..68c13c6989c99 100644
--- a/app/lib/server/oauth/oauth.js
+++ b/app/lib/server/oauth/oauth.js
@@ -24,7 +24,14 @@ Accounts.registerLoginHandler(function(options) {
 		serviceName: String,
 	}));
 
-	const service = AccessTokenServices[options.serviceName];
+	// Check if service is configured and therefore a custom OAuth
+	const config = ServiceConfiguration.configurations.findOne({ service: options.serviceName });
+
+	let service = AccessTokenServices[options.serviceName];
+
+	if (!service && config) {
+		service = AccessTokenServices.custom;
+	}
 
 	// Skip everything if there's no service set by the oauth middleware
 	if (!service) {
@@ -32,11 +39,11 @@ Accounts.registerLoginHandler(function(options) {
 	}
 
 	// Make sure we're configured
-	if (!ServiceConfiguration.configurations.findOne({ service: service.serviceName })) {
+	if (!config) {
 		throw new ServiceConfiguration.ConfigError();
 	}
 
-	if (!_.contains(Accounts.oauth.serviceNames(), service.serviceName)) {
+	if (!_.contains(Accounts.oauth.serviceNames(), options.serviceName)) {
 		// serviceName was not found in the registered services list.
 		// This could happen because the service never registered itself or
 		// unregisterService was called on it.
@@ -44,14 +51,14 @@ Accounts.registerLoginHandler(function(options) {
 			type: 'oauth',
 			error: new Meteor.Error(
 				Accounts.LoginCancelledError.numericError,
-				`No registered oauth service found for: ${ service.serviceName }`
+				`No registered oauth service found for: ${ options.serviceName }`
 			),
 		};
 	}
 
 	const oauthResult = service.handleAccessTokenRequest(options);
 
-	return Accounts.updateOrCreateUserFromExternalService(service.serviceName, oauthResult.serviceData, oauthResult.options);
+	return Accounts.updateOrCreateUserFromExternalService(options.serviceName, oauthResult.serviceData, oauthResult.options);
 });