diff --git a/src/vs/editor/browser/services/openerService.ts b/src/vs/editor/browser/services/openerService.ts
index c42f82fdb26dea91248a5c0d53894f3b971a02db..8a122c18fc5da8c2e76f14ca234b83893571dcaa 100644
--- a/src/vs/editor/browser/services/openerService.ts
+++ b/src/vs/editor/browser/services/openerService.ts
@@ -13,7 +13,7 @@ import { equalsIgnoreCase } from 'vs/base/common/strings';
 import { URI } from 'vs/base/common/uri';
 import { ICodeEditorService } from 'vs/editor/browser/services/codeEditorService';
 import { CommandsRegistry, ICommandService } from 'vs/platform/commands/common/commands';
-import { IOpener, IOpenerService, IValidator } from 'vs/platform/opener/common/opener';
+import { IOpener, IOpenerService, IValidator, IExternalUriResolver } from 'vs/platform/opener/common/opener';
 
 export class OpenerService extends Disposable implements IOpenerService {
 
@@ -21,6 +21,7 @@ export class OpenerService extends Disposable implements IOpenerService {
 
 	private readonly _openers = new LinkedList<IOpener>();
 	private readonly _validators = new LinkedList<IValidator>();
+	private readonly _resolvers = new LinkedList<IExternalUriResolver>();
 
 	constructor(
 		@ICodeEditorService private readonly _editorService: ICodeEditorService,
@@ -39,6 +40,11 @@ export class OpenerService extends Disposable implements IOpenerService {
 		return { dispose: remove };
 	}
 
+	registerExternalUriResolver(resolver: IExternalUriResolver): IDisposable {
+		const remove = this._resolvers.push(resolver);
+		return { dispose: remove };
+	}
+
 	async open(resource: URI, options?: { openToSide?: boolean, openExternal?: boolean }): Promise<boolean> {
 		// no scheme ?!?
 		if (!resource.scheme) {
@@ -118,7 +124,11 @@ export class OpenerService extends Disposable implements IOpenerService {
 		}
 	}
 
-	private _doOpenExternal(resource: URI): Promise<boolean> {
+	private async _doOpenExternal(resource: URI): Promise<boolean> {
+		for (const resolver of this._resolvers.toArray()) {
+			resource = await resolver.resolveExternalUri(resource);
+		}
+
 		dom.windowOpenNoOpener(encodeURI(resource.toString(true)));
 
 		return Promise.resolve(true);
diff --git a/src/vs/platform/opener/common/opener.ts b/src/vs/platform/opener/common/opener.ts
index 8563f3fa2af386595e7976939b8eea6da0810382..0c9a243a952c60eb17819337cb5fd57e483d7c82 100644
--- a/src/vs/platform/opener/common/opener.ts
+++ b/src/vs/platform/opener/common/opener.ts
@@ -5,7 +5,7 @@
 
 import { URI } from 'vs/base/common/uri';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
-import { IDisposable } from 'vs/base/common/lifecycle';
+import { IDisposable, Disposable } from 'vs/base/common/lifecycle';
 
 export const IOpenerService = createDecorator<IOpenerService>('openerService');
 
@@ -18,6 +18,10 @@ export interface IValidator {
 	shouldOpen(resource: URI): Promise<boolean>;
 }
 
+export interface IExternalUriResolver {
+	resolveExternalUri(resource: URI): Promise<URI>;
+}
+
 export interface IOpenerService {
 
 	_serviceBrand: undefined;
@@ -29,10 +33,15 @@ export interface IOpenerService {
 
 	/**
 	 * Register a participant that can validate if the URI resource be opened.
-	 * validators are run before openers.
+	 * Validators are run before openers.
 	 */
 	registerValidator(validator: IValidator): IDisposable;
 
+	/**
+	 * Register a participant that can resolve an external URI resource to be opened.
+	 */
+	registerExternalUriResolver(resolver: IExternalUriResolver): IDisposable;
+
 	/**
 	 * Opens a resource, like a webaddress, a document uri, or executes command.
 	 *
@@ -45,7 +54,8 @@ export interface IOpenerService {
 
 export const NullOpenerService: IOpenerService = Object.freeze({
 	_serviceBrand: undefined,
-	registerOpener() { return { dispose() { } }; },
-	registerValidator() { return { dispose() { } }; },
+	registerOpener() { return Disposable.None; },
+	registerValidator() { return Disposable.None; },
+	registerExternalUriResolver() { return Disposable.None; },
 	open() { return Promise.resolve(false); },
 });
diff --git a/src/vs/workbench/contrib/url/common/externalUriResolver.ts b/src/vs/workbench/contrib/url/common/externalUriResolver.ts
new file mode 100644
index 0000000000000000000000000000000000000000..454d76644b6231f3c976029122a8b68806262a93
--- /dev/null
+++ b/src/vs/workbench/contrib/url/common/externalUriResolver.ts
@@ -0,0 +1,26 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { Disposable } from 'vs/base/common/lifecycle';
+import { IOpenerService } from 'vs/platform/opener/common/opener';
+import { IWorkbenchContribution } from 'vs/workbench/common/contributions';
+import { IWorkbenchEnvironmentService } from 'vs/workbench/services/environment/common/environmentService';
+
+export class ExternalUriResolverContribution extends Disposable implements IWorkbenchContribution {
+	constructor(
+		@IOpenerService _openerService: IOpenerService,
+		@IWorkbenchEnvironmentService _workbenchEnvironmentService: IWorkbenchEnvironmentService,
+	) {
+		super();
+
+		if (_workbenchEnvironmentService.options && _workbenchEnvironmentService.options.resolveExternalUri) {
+			this._register(_openerService.registerExternalUriResolver({
+				resolveExternalUri: async (resource) => {
+					return _workbenchEnvironmentService.options!.resolveExternalUri!(resource);
+				}
+			}));
+		}
+	}
+}
diff --git a/src/vs/workbench/contrib/url/common/url.contribution.ts b/src/vs/workbench/contrib/url/common/url.contribution.ts
index f51bd6d3f03b5678883f4ad9a31d58470d0c5853..e299262de0573f1a0df496c4b5db1589e66344aa 100644
--- a/src/vs/workbench/contrib/url/common/url.contribution.ts
+++ b/src/vs/workbench/contrib/url/common/url.contribution.ts
@@ -14,9 +14,10 @@ import { Registry } from 'vs/platform/registry/common/platform';
 import { IURLService } from 'vs/platform/url/common/url';
 import { Extensions as ActionExtensions, IWorkbenchActionRegistry } from 'vs/workbench/common/actions';
 import { Extensions as WorkbenchExtensions, IWorkbenchContributionsRegistry } from 'vs/workbench/common/contributions';
+import { ExternalUriResolverContribution } from 'vs/workbench/contrib/url/common/externalUriResolver';
 import { configureTrustedDomainSettingsCommand } from 'vs/workbench/contrib/url/common/trustedDomains';
-import { OpenerValidatorContributions } from 'vs/workbench/contrib/url/common/trustedDomainsValidator';
 import { TrustedDomainsFileSystemProvider } from 'vs/workbench/contrib/url/common/trustedDomainsFileSystemProvider';
+import { OpenerValidatorContributions } from 'vs/workbench/contrib/url/common/trustedDomainsValidator';
 
 export class OpenUrlAction extends Action {
 	static readonly ID = 'workbench.action.url.openUrl';
@@ -65,3 +66,7 @@ Registry.as<IWorkbenchContributionsRegistry>(WorkbenchExtensions.Workbench).regi
 	TrustedDomainsFileSystemProvider,
 	LifecyclePhase.Ready
 );
+Registry.as<IWorkbenchContributionsRegistry>(WorkbenchExtensions.Workbench).registerWorkbenchContribution(
+	ExternalUriResolverContribution,
+	LifecyclePhase.Ready
+);
diff --git a/src/vs/workbench/workbench.web.api.ts b/src/vs/workbench/workbench.web.api.ts
index cd4351d60167c3e7e8f6bd3d3c0315356bfef773..38bb092333d12bd40b4b40e9242ba84ac3d563d9 100644
--- a/src/vs/workbench/workbench.web.api.ts
+++ b/src/vs/workbench/workbench.web.api.ts
@@ -90,6 +90,11 @@ interface IWorkbenchConstructionOptions {
 	 * Experimental: Support for update reporting.
 	 */
 	updateProvider?: IUpdateProvider;
+
+	/**
+	 * Experimental: Resolves an external uri before it is opened.
+	 */
+	readonly resolveExternalUri?: (uri: URI) => Promise<URI>;
 }
 
 /**