diff --git a/types/psi/index.d.ts b/types/psi/index.d.ts
new file mode 100644
index 0000000000..75f27a50ca
--- /dev/null
+++ b/types/psi/index.d.ts
@@ -0,0 +1,181 @@
+// Type definitions for psi 4.0
+// Project: https://github.com/GoogleChromeLabs/psi#readme
+// Definitions by: Piotr Błażejewicz <https://github.com/peterblazejewicz>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+/**
+ * PageSpeed Insights with reporting
+ */
+declare function psi(url: string, options?: psi.Options): Promise<psi.ResponseData>;
+
+declare namespace psi {
+    /**
+     * Output the formatted report to the terminal.
+     */
+    function output(url: string, options?: Options): Promise<ResponseData>;
+
+    interface Options {
+        /**
+         * When using this module for a production-level build process,
+         * registering for an API key from the Google Developer Console is recommended.
+         */
+        key?: string;
+        nokey?: string;
+        /**
+         * Strategy to use when analyzing the page.
+         * @default 'mobile'
+         */
+        strategy?: 'mobile' | 'desktop';
+        /**
+         * Locale results should be generated in.
+         * @default 'en_US'
+         */
+        locale?: string;
+        /**
+         * Threshold score to pass the PageSpeed test. Useful for setting a performance budget.
+         * @default 70
+         */
+        treshold?: number;
+    }
+
+    interface Experience {
+        id: string;
+        metrics: {
+            [key: string]: {
+                percentile: number;
+                distributions: Array<{
+                    min: number;
+                    max: number;
+                    proportion: number;
+                }>;
+                category: string;
+            };
+        };
+        overall_category: string;
+        initial_url: string;
+    }
+
+    interface Environment {
+        networkUserAgent: string;
+        hostUserAgent: string;
+        benchmarkIndex: number;
+    }
+
+    interface ConfigSettings {
+        emulatedFormFactor: string;
+        locale: string;
+        onlyCategories: object;
+    }
+
+    interface Audit {
+        id: string;
+        title: string;
+        description: string;
+        score: object;
+        displayValue: string;
+        scoreDisplayMode: string;
+        explanation: string;
+        errorMessage: string;
+        warnings: object;
+        details: {
+            [key: string]: object;
+        };
+    }
+
+    interface AuditRef {
+        id: string;
+        weight: number;
+        group: string;
+    }
+
+    interface Category {
+        id: string;
+        title: string;
+        description: string;
+        score: object;
+        manualDescription: string;
+        auditRefs: AuditRef[];
+    }
+
+    interface CategoryGroup {
+        title: string;
+        description: string;
+    }
+
+    interface RuntimeError {
+        code: string;
+        message: string;
+    }
+
+    interface Timing {
+        total: number;
+    }
+
+    interface RendererFormattedStrings {
+        varianceDisclaimer: string;
+        opportunityResourceColumnLabel: string;
+        opportunitySavingsColumnLabel: string;
+        errorMissingAuditInfo: string;
+        errorLabel: string;
+        warningHeader: string;
+        auditGroupExpandTooltip: string;
+        passedAuditsGroupTitle: string;
+        notApplicableAuditsGroupTitle: string;
+        manualAuditsGroupTitle: string;
+        toplevelWarningsMessage: string;
+        scorescaleLabel: string;
+        crcLongestDurationLabel: string;
+        crcInitialNavigation: string;
+        lsPerformanceCategoryDescription: string;
+        labDataTitle: string;
+    }
+
+    // tslint:disable-next-line:interface-name I18N is established convention
+    interface I18N {
+        rendererFormattedStrings: RendererFormattedStrings;
+    }
+
+    interface Version {
+        major: number;
+        minor: number;
+    }
+
+    interface ResponseData {
+        data: Result;
+    }
+
+    interface LighthouseResult {
+        requestedUrl: string;
+        finalUrl: string;
+        lighthouseVersion: string;
+        userAgent: string;
+        fetchTime: string;
+        environment: Environment;
+        runWarnings: string[];
+        configSettings: ConfigSettings;
+        audits: {
+            [key: string]: Audit;
+        };
+        categories: {
+            [key: string]: Category;
+        };
+        categoryGroups: {
+            [key: string]: CategoryGroup;
+        };
+        runtimeError: RuntimeError;
+        timing: Timing;
+        i18n: I18N;
+    }
+    interface Result {
+        captchaResult: string;
+        kind: string;
+        id: string;
+        loadingExperience: Experience;
+        originLoadingExperience: Experience;
+        lighthouseResult: LighthouseResult;
+        analysisUTCTimestamp: string;
+        version: Version;
+    }
+}
+
+export = psi;
diff --git a/types/psi/psi-tests.ts b/types/psi/psi-tests.ts
new file mode 100644
index 0000000000..4b16ef054c
--- /dev/null
+++ b/types/psi/psi-tests.ts
@@ -0,0 +1,24 @@
+/// <reference types="node" />
+import psi = require('psi');
+
+(async () => {
+    const { data } = await psi('https://theverge.com');
+    console.log('Speed score:', data.lighthouseResult.categories.performance.score);
+    await psi.output('https://theverge.com');
+    console.log('Done');
+    const data2 = await psi('https://theverge.com', {
+        nokey: 'true',
+        strategy: 'desktop',
+    });
+    console.log('Speed score:', data2.data.lighthouseResult.categories.performance.score);
+    console.log(data.lighthouseResult.audits['screenshot-thumbnails'].details.items);
+})();
+psi('https://theverge.com').then(({ data }) => {
+    console.log('Speed score:', data.lighthouseResult.categories.performance.score);
+});
+psi('https://theverge.com', {
+    nokey: 'true',
+    strategy: 'desktop',
+}).then(data2 => {
+    console.log('Speed score:', data2.data.lighthouseResult.categories.performance.score);
+});
diff --git a/types/psi/tsconfig.json b/types/psi/tsconfig.json
new file mode 100644
index 0000000000..4175835c56
--- /dev/null
+++ b/types/psi/tsconfig.json
@@ -0,0 +1,23 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "psi-tests.ts"
+    ]
+}
diff --git a/types/psi/tslint.json b/types/psi/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/psi/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }