diff --git a/CHANGELOG.md b/CHANGELOG.md
index ec2af0397..de492fb3f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 ## Unreleased
 ### Added
 - Added Storefront API client under `Shopify.Clients.Storefront`
+- Add `isActive()` method to `Session` class to check if session is active, replace `Session` with `SessionInterface` when used as a type [#153](https://github.com/Shopify/shopify-node-api/pull/153)
 
 ## [1.2.1] - 2021-03-26
 ### Added
diff --git a/docs/usage/customsessions.md b/docs/usage/customsessions.md
index c32e0bab2..78ff0b1ce 100644
--- a/docs/usage/customsessions.md
+++ b/docs/usage/customsessions.md
@@ -12,8 +12,8 @@ When you're ready to deploy your app and run it in production, you'll need to se
 
 | Method | Arg type | Return type  | Notes  |
 | ------- | ------- | ------------ | -------|
-| `storeCallback`  | `Session` | `Promise<boolean>` | Takes in the `Session` to be stored or updated, returns a `boolean` (`true` if stored successfully). <br/> This callback is used both to save new a `Session` and to **update an existing `Session`**.                                                                                                                        |
-| `loadCallback`   | `string`  | `Promise<Session \| Record<string, unknown> \| undefined> ` | Takes in the id of the `Session` to load (as a `string`) and returns either an instance of a `Session`, an object to be used to instantiate a `Session`, or `undefined` if no record is found for the specified id. |
+| `storeCallback`  | `SessionInterface` | `Promise<boolean>` | Takes in the `Session` to be stored or updated, returns a `boolean` (`true` if stored successfully). <br/> This callback is used both to save new a `Session` and to **update an existing `Session`**.                                                                                                                        |
+| `loadCallback`   | `string`  | `Promise<SessionInterface \| Record<string, unknown> \| undefined> ` | Takes in the id of the `Session` to load (as a `string`) and returns either an instance of a `Session`, an object to be used to instantiate a `Session`, or `undefined` if no record is found for the specified id. |
 | `deleteCallback` | `string`  | `Promise<boolean>` | Takes in the id of the `Session` to load (as a `string`) and returns a  `booelan` (`true` if deleted successfully). |
 
 ## Example usage
diff --git a/src/auth/session/session.ts b/src/auth/session/session.ts
index b3b6ce232..c4dc36f29 100644
--- a/src/auth/session/session.ts
+++ b/src/auth/session/session.ts
@@ -1,9 +1,12 @@
 import {OnlineAccessInfo} from '../oauth/types';
+import {Context} from '../../context';
+
+import {SessionInterface} from './types';
 
 /**
  * Stores App information from logged in merchants so they can make authenticated requests to the Admin API.
  */
-class Session {
+class Session implements SessionInterface {
   public static cloneSession(session: Session, newId: string): Session {
     const newSession = new Session(newId);
 
@@ -27,6 +30,14 @@ class Session {
   public onlineAccessInfo?: OnlineAccessInfo;
 
   constructor(readonly id: string) {}
+
+  public isActive(): boolean {
+    const scopesUnchanged = Context.SCOPES.equals(this.scope);
+    if (scopesUnchanged && this.accessToken && (!this.expires || this.expires >= new Date())) {
+      return true;
+    }
+    return false;
+  }
 }
 
 export {Session};
diff --git a/src/auth/session/session_storage.ts b/src/auth/session/session_storage.ts
index 8c236c26a..c5ee2a5c4 100644
--- a/src/auth/session/session_storage.ts
+++ b/src/auth/session/session_storage.ts
@@ -1,4 +1,4 @@
-import {Session} from './session';
+import {SessionInterface} from './types';
 
 /**
  * Defines the strategy to be used to store sessions for the Shopify App.
@@ -10,14 +10,14 @@ interface SessionStorage {
    *
    * @param session Session to store
    */
-  storeSession(session: Session): Promise<boolean>;
+  storeSession(session: SessionInterface): Promise<boolean>;
 
   /**
    * Loads a session from storage.
    *
    * @param id Id of the session to load
    */
-  loadSession(id: string): Promise<Session | undefined>;
+  loadSession(id: string): Promise<SessionInterface | undefined>;
 
   /**
    * Deletes a session from storage.
diff --git a/src/auth/session/storage/custom.ts b/src/auth/session/storage/custom.ts
index 39c395934..44d351ccd 100644
--- a/src/auth/session/storage/custom.ts
+++ b/src/auth/session/storage/custom.ts
@@ -1,11 +1,12 @@
 import {Session} from '../session';
+import {SessionInterface} from '../types';
 import {SessionStorage} from '../session_storage';
 import * as ShopifyErrors from '../../../error';
 
 export class CustomSessionStorage implements SessionStorage {
   constructor(
-    readonly storeCallback: (session: Session) => Promise<boolean>,
-    readonly loadCallback: (id: string) => Promise<Session | Record<string, unknown> | undefined>,
+    readonly storeCallback: (session: SessionInterface) => Promise<boolean>,
+    readonly loadCallback: (id: string) => Promise<SessionInterface | Record<string, unknown> | undefined>,
     readonly deleteCallback: (id: string) => Promise<boolean>,
   ) {
     this.storeCallback = storeCallback;
@@ -13,7 +14,7 @@ export class CustomSessionStorage implements SessionStorage {
     this.deleteCallback = deleteCallback;
   }
 
-  public async storeSession(session: Session): Promise<boolean> {
+  public async storeSession(session: SessionInterface): Promise<boolean> {
     try {
       return await this.storeCallback(session);
     } catch (error) {
@@ -23,8 +24,8 @@ export class CustomSessionStorage implements SessionStorage {
     }
   }
 
-  public async loadSession(id: string): Promise<Session | undefined> {
-    let result: Session | Record<string, unknown> | undefined;
+  public async loadSession(id: string): Promise<SessionInterface | undefined> {
+    let result: SessionInterface | Record<string, unknown> | undefined;
     try {
       result = await this.loadCallback(id);
     } catch (error) {
@@ -41,7 +42,7 @@ export class CustomSessionStorage implements SessionStorage {
         return result;
       } else if (result instanceof Object && 'id' in result) {
         let session = new Session(result.id as string);
-        session = {...session, ...result};
+        session = {...session, ...result as SessionInterface};
 
         if (session.expires && typeof session.expires === 'string') {
           session.expires = new Date(session.expires);
diff --git a/src/auth/session/storage/memory.ts b/src/auth/session/storage/memory.ts
index eaef1f024..14142f45d 100644
--- a/src/auth/session/storage/memory.ts
+++ b/src/auth/session/storage/memory.ts
@@ -1,15 +1,15 @@
-import {Session} from '../session';
+import {SessionInterface} from '../types';
 import {SessionStorage} from '../session_storage';
 
 export class MemorySessionStorage implements SessionStorage {
-  private sessions: { [id: string]: Session; } = {};
+  private sessions: { [id: string]: SessionInterface; } = {};
 
-  public async storeSession(session: Session): Promise<boolean> {
+  public async storeSession(session: SessionInterface): Promise<boolean> {
     this.sessions[session.id] = session;
     return true;
   }
 
-  public async loadSession(id: string): Promise<Session | undefined> {
+  public async loadSession(id: string): Promise<SessionInterface | undefined> {
     return this.sessions[id] || undefined;
   }
 
diff --git a/src/auth/session/test/custom.test.ts b/src/auth/session/storage/test/custom.test.ts
similarity index 97%
rename from src/auth/session/test/custom.test.ts
rename to src/auth/session/storage/test/custom.test.ts
index 79b2a4c29..b556c3133 100644
--- a/src/auth/session/test/custom.test.ts
+++ b/src/auth/session/storage/test/custom.test.ts
@@ -1,8 +1,8 @@
-import '../../../test/test_helper';
+import '../../../../test/test_helper';
 
-import {Session} from '../session';
-import {CustomSessionStorage} from '../storage/custom';
-import {SessionStorageError} from '../../../error';
+import {Session} from '../../session';
+import {CustomSessionStorage} from '../custom';
+import {SessionStorageError} from '../../../../error';
 
 describe('custom session storage', () => {
   test('can perform actions', async () => {
diff --git a/src/auth/session/test/memory.test.ts b/src/auth/session/storage/test/memory.test.ts
similarity index 87%
rename from src/auth/session/test/memory.test.ts
rename to src/auth/session/storage/test/memory.test.ts
index 98e06e9a1..8ac9e8930 100644
--- a/src/auth/session/test/memory.test.ts
+++ b/src/auth/session/storage/test/memory.test.ts
@@ -1,7 +1,7 @@
-import '../../../test/test_helper';
+import '../../../../test/test_helper';
 
-import {Session} from '../session';
-import {MemorySessionStorage} from '../storage/memory';
+import {Session} from '../../session';
+import {MemorySessionStorage} from '../memory';
 
 test('can store and delete sessions in memory', async () => {
   const sessionId = 'test_session';
diff --git a/src/auth/session/test/session.test.ts b/src/auth/session/test/session.test.ts
new file mode 100644
index 000000000..cf37463b6
--- /dev/null
+++ b/src/auth/session/test/session.test.ts
@@ -0,0 +1,35 @@
+import '../../../test/test_helper';
+import {Session} from '..';
+
+describe('session', () => {
+  it('can clone a session', () => {
+    const session = new Session('original');
+    const sessionClone = Session.cloneSession(session, 'new');
+
+    expect(session.id).not.toEqual(sessionClone.id);
+    expect(session.shop).toStrictEqual(sessionClone.shop);
+    expect(session.state).toStrictEqual(sessionClone.state);
+    expect(session.scope).toStrictEqual(sessionClone.scope);
+    expect(session.expires).toStrictEqual(sessionClone.expires);
+    expect(session.isOnline).toStrictEqual(sessionClone.isOnline);
+    expect(session.accessToken).toStrictEqual(sessionClone.accessToken);
+    expect(session.onlineAccessInfo).toStrictEqual(sessionClone.onlineAccessInfo);
+  });
+});
+
+describe('isActive', () => {
+  it('returns true if session is active', () => {
+    const session = new Session('active');
+    session.scope = 'test_scope';
+    session.accessToken = 'indeed';
+    session.expires = new Date(Date.now() + 86400);
+    expect(session.isActive()).toBeTruthy();
+  });
+
+  it('returns false if session is not active', () => {
+    const session = new Session('not_active');
+    session.scope = 'not_same';
+    session.expires = new Date(Date.now() - 1);
+    expect(session.isActive()).toBeFalsy();
+  });
+});
diff --git a/src/auth/session/types.ts b/src/auth/session/types.ts
new file mode 100644
index 000000000..39a450c8d
--- /dev/null
+++ b/src/auth/session/types.ts
@@ -0,0 +1,13 @@
+import {OnlineAccessInfo} from '../oauth/types';
+
+export interface SessionInterface {
+  readonly id: string;
+  shop: string;
+  state: string;
+  scope: string;
+  expires?: Date;
+  isOnline?: boolean;
+  accessToken?: string;
+  onlineAccessInfo?: OnlineAccessInfo;
+  isActive(): boolean;
+}
diff --git a/src/auth/types.ts b/src/auth/types.ts
new file mode 100644
index 000000000..9907ded20
--- /dev/null
+++ b/src/auth/types.ts
@@ -0,0 +1,2 @@
+export * from './oauth/types';
+export * from './session/types';
diff --git a/src/base_types.ts b/src/base_types.ts
index 91b2a965b..d9ce7d9f1 100644
--- a/src/base_types.ts
+++ b/src/base_types.ts
@@ -1,5 +1,5 @@
-import {SessionStorage} from './auth/session';
 import {AuthScopes} from './auth/scopes';
+import {SessionStorage} from './auth/session/session_storage';
 
 export interface ContextParams {
   API_KEY: string;
diff --git a/src/context.ts b/src/context.ts
index 1ce57277b..c86fefe3b 100644
--- a/src/context.ts
+++ b/src/context.ts
@@ -1,5 +1,6 @@
 import * as ShopifyErrors from './error';
-import {SessionStorage, MemorySessionStorage} from './auth/session';
+import {SessionStorage} from './auth/session/session_storage';
+import {MemorySessionStorage} from './auth/session/storage/memory';
 import {ApiVersion, ContextParams} from './base_types';
 import {AuthScopes} from './auth/scopes';
 
diff --git a/src/types.ts b/src/types.ts
index 027093a90..17ffebe52 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,5 +1,5 @@
 export * from './base_types';
-export * from './auth/oauth/types';
+export * from './auth/types';
 export * from './clients/types';
 export * from './utils/types';
 export * from './webhooks/types';