Testing with Postman

Postman is an API client that lets you send requests and inspect responses without writing any code. Pair it with a simulated vehicle and you can exercise the whole Smartcar API, including commands and webhooks, before you connect a real vehicle. By the end of this guide you will have an access token, a simulated vehicle, and a working request that returns vehicle data.

What you’ll need

A Postman account and the Postman app
A Smartcar Dashboard account
An application on the v3 API. See API Authentication Setup if you aren’t sure.

Step 1: Fork the collection and environment

Smartcar publishes both a collection and an environment in the Smartcar API workspace on the Postman API Network.

Fork the collection

Open the Smartcar API Collection and select Fork to copy it into your own workspace.

Fork the environment

Do the same for the SmartcarApi Variables environment in that workspace. It holds the base URLs plus the placeholders you fill in below.

Select the environment

In Postman, choose SmartcarApi Variables from the environment selector. Requests fail with unresolved {{variable}} errors if no environment is selected.

The environment defines these variables:

Variable	Description
`clientId`	Your application’s client ID
`clientSecret`	A client secret you generate in the Dashboard
`accessToken`	Set automatically when you run Client Credentials
`vehicleId`	The vehicle you want to query
`userId`	The user the vehicle is connected to
`iamUrl`, `vehicleUrl`, `managementUrl`, `compatibilityUrl`	Smartcar base URLs, prefilled

Step 2: Add your API credentials

In the Smartcar Dashboard, go to Configuration > API credentials. Copy your Client ID, then generate a Client Secret.

API credentials tab in the Smartcar Dashboard Configuration page

Paste both values into the clientId and clientSecret variables in your Postman environment.

The client secret is shown only once, and it grants access to every vehicle connected to your application. Store it somewhere secure and never commit it or share a Postman workspace that contains it.

Step 3: Get an access token

Run the Client Credentials request. It posts your credentials to the token endpoint and returns an application-level access token:

{
  "access_token": "{access_token}",
  "token_type": "Bearer",
  "expires_in": 3600
}

The request has a test script that writes access_token into the accessToken environment variable, so every other request in the collection picks it up automatically.

Access tokens are valid for 1 hour and there is no refresh token. When requests start failing, run Client Credentials again. See Request an access token for the full reference.

Step 4: Create a simulated vehicle

In the Dashboard, open the Simulator tab and select Add simulated vehicle. Choose a powertrain type, give the vehicle a name, and leave Automatically connect to application enabled so the vehicle is ready to query straight away.

Add simulated vehicle modal in the Smartcar Dashboard

The powertrain type you pick (BEV, PHEV, HEV, or ICE) determines which signals and commands are available. Simulated vehicles are granted all compatible permissions by default. Once the vehicle is created, copy its Vehicle ID and User ID from the Simulator table into the vehicleId and userId environment variables in Postman.

Simulated vehicles appear in your connections and logs with Simulated as the make and the powertrain type as the model, for example 2023 Simulated BEV.

Step 5: Confirm the connection

Run the Connections request to list the vehicles connected to your application. To see only simulated vehicles, enable the filter[vehicle.mode] query parameter and set it to simulated. Your new vehicle should appear with the same ID you copied in the previous step. If it doesn’t, the vehicle was likely created in a disconnected state, so connect it from the Simulator before continuing.

Step 6: Read vehicle data

With accessToken, vehicleId, and userId all set, run:

Vehicle to get the vehicle’s details
Signals to read every signal the vehicle exposes
Signal to read one signal, for example charge-chargetimers

Signal requests send the user’s ID in the sc-user-id header, which the collection populates from {{userId}}. A request that returns an authorization error is usually missing that variable.

Step 7: Send a command

Simulated vehicles support these commands:

Run Commands security/lock, then return to the vehicle in the Simulator and select Refresh to see the updated state.

Step 8: Change the vehicle state

The Simulator gives you direct control over the vehicle’s data. Open the vehicle’s Vehicle state tab, edit any signals you want, and select Publish. Re-run your Postman requests and the responses reflect the new state.

Configuring vehicle signals in the Smartcar Vehicle Simulator

This is also how you reproduce errors. For example, set Transmission.GearState to DRIVE and a lock command returns a VEHICLE_STATE:IN_MOTION error, or uncheck a permission under VehicleUserAccount.Permissions and the matching request returns a permission error.

Simulated vehicles have no rate limits and no command latency, so responses come back immediately. Live vehicles behave differently on both counts.

Testing Smartcar Connect in simulated mode

The steps above use application-level tokens, which is the recommended way to reach both live and simulated vehicles. If your integration uses the OAuth 2.0 authorization code flow instead, you can rehearse the vehicle owner’s experience against a simulated vehicle.

Create the vehicle disconnected

Turn off Automatically connect to application when creating the simulated vehicle, or disconnect an existing one.

Open the Connect modal

Select Connect manually via Smartcar Connect to get a Connect URL with mode=simulated and the credentials to sign in with.

Complete the flow

Launch the URL, pick any brand, and sign in with the generated credentials.

Smartcar Connect running in simulated mode

The simulated Connect flow uses response_type=none, so it does not return a per-vehicle access token. To receive an authorization code you can exchange, launch Connect with response_type=code and a configured redirect URI.

Troubleshooting

My requests return an unresolved variable error

Select the SmartcarApi Variables environment in Postman. Without it, {{clientId}} and the other placeholders are never substituted.

Requests that worked a moment ago now fail to authorize

Access tokens expire after 1 hour and there is no refresh token. Run Client Credentials again to mint a new one.

I'm getting a permission error on a signal or command

Check that the permission is still granted. Simulated vehicles grant all compatible permissions by default, but they can be toggled off under the VehicleUserAccount.Permissions signal. See Permissions.Also confirm the signal or command is supported by the powertrain type you chose.

My simulated vehicle doesn't appear in Connections

The vehicle was probably created with Automatically connect to application turned off, or it was disconnected later. Connect it from the Simulator, then run Connections again.

What’s next

Test your webhooks

Subscribe a simulated vehicle to an integration and trigger deliveries by publishing state changes.

Browse the signals catalog

See every signal you can read and configure.

Generate a client

Download the raw OpenAPI documents to generate code or feed the schema into your own tooling.

Getting Started

How-To Guides

Tutorials

Dashboard

Testing with Postman

What you’ll need

Step 1: Fork the collection and environment

Step 2: Add your API credentials

Step 3: Get an access token

Step 4: Create a simulated vehicle

Step 5: Confirm the connection

Step 6: Read vehicle data

Step 7: Send a command

Step 8: Change the vehicle state

Testing Smartcar Connect in simulated mode

Troubleshooting

What’s next

Test your webhooks

Browse the signals catalog

Generate a client

​What you’ll need

​Step 1: Fork the collection and environment

​Step 2: Add your API credentials

​Step 3: Get an access token

​Step 4: Create a simulated vehicle

​Step 5: Confirm the connection

​Step 6: Read vehicle data

​Step 7: Send a command

​Step 8: Change the vehicle state

​Testing Smartcar Connect in simulated mode

​Troubleshooting

​What’s next

Test your webhooks

Browse the signals catalog

Generate a client

What you’ll need

Step 1: Fork the collection and environment

Step 2: Add your API credentials

Step 3: Get an access token

Step 4: Create a simulated vehicle

Step 5: Confirm the connection

Step 6: Read vehicle data

Step 7: Send a command

Step 8: Change the vehicle state

Testing Smartcar Connect in simulated mode

Troubleshooting

What’s next