Marketo API Quick-Start Guide

Get a guided walkthrough of how to make your first Marketo API request using Postman and then integrate this request into Zapier or a script in your favorite programming language.


If you are doing any repetitive work within Marketo e.g. bulk merging leads, bulk creating programs etc then you should look into using the Marketo API within code scripts or an automation tool such as Zapier to automate these processes.

This post will take you all the way from the Marketo API docs to making your first API requests in Postman to integrating these requests into Zapier actions or scripts in your favorite programming language.

N.B. If you want to get started with 100+ Marketo API requests in Postman then follow this link to join the “Marketo Maestros” team and access the “Marketo REST API” workspace. I have personally configured and tested all the requests in this collection so that they will work out of the box once you have exported this collection to your personal workspace and set up your own Marketo environment (see below).

What is an API?

Anyone can Google the technical definition of an API and what it does so I won’t go into that here. I will instead offer as layman a definition as possible.

Basically, an API is a collection of urls (called endpoints) to which you either retrieve information from (GET request) or post information to (POST request). You can learn how to make your first GET and POST requests in Postman below.

According to how the APIs are configured they will adhere to certain protocols and be defined as a certain type of API e.g. REST, SOAP. Although Marketo has a SOAP API, it is no longer under active development and their developers are focusing on the REST API moving forward. Marketo also has a JavaScript API but this API is used for enabling features like lead tracking, form data capture, and personalization on your Marketo landing pages or website and cannot be used to interface with leads and assets. Consequently, I will focus on the Marketo REST API for the remainder of this post.

Marketo API Documentation

For anyone looking to do any sort of automation in Marketo, the Marketo REST API documentation will become your bible, allowing you to retrieve information about leads and assets (landing pages, emails, programs) or modify them programmatically.

The Marketo REST API landing page has everything you need to get started by showing you how to set up an API user and get the “Client Id” and “Client Secret” needed for authentication.

Testing the Marketo API using Postman

Before integrating any API call into a script or an automation tool like Zapier, I recommend testing the API call out first in the free API testing tool, Postman. This way you can test that you are making the API request correctly and you can see what the output response from this request will look like.

Create a Marketo Environment & Variables

The first step in using Marketo API calls in Postman is to set up a Marketo environment and associated environment variables.

Marketo Environment & Variables in Postman
  1. Click on the “Manage Environments” icon to the right of the eye icon
  2. Click “Add” in the pop-up window that appears
  3. Name the environment e.g. “Marketo”
  4. Create 4 variables to contain the base URL, Client Id, Client Secret, and Bearer Token
    1. The values for the base URL, Client Id, and Client Secret can be found from the authentication section in the Marketo API docs. The base URL should be the same as the “Endpoint” and “Identity” URLs but with the “/rest” or “/identity” removed from the end e.g. base_url = https://xxx-xxx-xxx.mktorest.com

Making Your First Marketo API GET Request

The Marketo API request that you will use the most whether in Postman, scripts, or Zapier will always be the request to get an access token since this token is required to authenticate all other requests.

  1. Click on “New” in the top left-hand corner of the screen
  2. Select “Request”
  3. Name the request
  4. Select a collection to store the request or use the “Create Collection” option to create a new collection to store all your Marketo API requests.
  5. Paste {{base_url}}/identity/oauth/token?grant_type=client_credentials&client_id={{client_id}}&client_secret={{client_secret}} into the URL bar
    1. The request type dropdown is already set to “Get”
    2. The 3 variables we created earlier are brought in using curly brackets
    3. All 3 query parameters specified in the request URL automatically populate the “Params” tab beneath the URL bar
  6. Ensure that your Marketo environment is selected in the environment dropdown so that the request can access the 3 variables above
  7. Switch to the “Tests” tab
  8. Paste the code below into the “Tests” window
    1. This code will take the “access_token” value returned from Marketo and automatically store it in the “bearer_token” variable

var jsonData = pm.response.json();
pm.environment.set("bearer_token", jsonData.access_token);

  1. Click “Save”
  2. Click “Send”
Marketo API GET request for authorization in Postman

Bingo Bango! You have now made your first Marketo API request. What’s more, thanks to the code we pasted in the “Tests” tab we now have the access token stored as a variable that we can use in all other request we make in Postman (see section below). This Marketo authorization token only has a lifetime of 3600 seconds so you will need to run this authorization request regularly to get valid tokens.

Making Your First Marketo API POST Request

  1. Click on “New” in the top left-hand corner of the screen
  2. Select “Request”
  3. Name the request
  4. Select your Marketo API Collection
  5. Paste {{base_url}}/rest/asset/v1/program/1234.json into the URL bar
    1. Replace “1234” with the program id of a program that you can use for testing
      1. A program id can be extracted from the URL displayed when clicking on a program e.g. https://engage-ab.marketo.com/?munchkinId=xxx-xxx-xxx#/classic/PG1234A1
  6. Ensure that your Marketo environment is selected in the environment dropdown so that the request can access the base_url variable above
  7. Switch to the “Authorization” tab
  8. Set the “Type” to “Bearer Token”
  9. Paste “{{bearer_token}}” into the “Token” field
    1. This bear_token variable will automatically be populated with the access token from the GET request we made above
  10. Switch to the “Body” tab
  11. Select the “x-www-form-urlencoded” radio button
  12. Set the “Key” to “description” and “Value” to “My First Marketo API POST Request”
  13. Click “Save”
  14. Click “Send”
Marketo API POST request to update program description in Postman

Et Voila! Check the response in the Postman console to see how the description of the program was updated. The skeptics among us can check the description of the program in Marketo to see that it has indeed been updated!

Using the Marketo API in your Favorite Coding Language

One of the best features of Postman for beginners is its ability to output the code for any request you create in any of 17 languages ranging from C to JavaScript to Python.

  1. Click the “Code” link just under the “Send” button
  2. Select your preferred language and library combination on the left-hand side
  3. Copy the code that appears in the window
Python generated code for the program update POST request

Now that you have the ability to create Marketo API requests in your programming language of choice you can now embed these requests in scripts to unlock more advanced interaction with leads and assets in Marketo. Alternatively, you can now use these generated code snippets within Zapier to make Marketo API requests.

As an aside, there is a Marketo REST API library for Python that will allow you to make requests very easily, however, if you intend to make Marketo API requests within Zapier then you will not be able to use this library. Zapier currently uses Python version 3.7 and it does not allow you to import custom libraries. Therefore, you will have to follow the steps above to get the code for the request and then follow the steps below to make the request from within Zapier.

Using the Marketo API in Zapier

As you might have already guessed, Zapier is built entirely on APIs to offer integrations with many different software tools through an easy to use drag and drop builder. However, sometimes Zapier will not have an integration with a platform you require or they will not have certain functionality available for an integrated platform.

For example the only trigger available in Zapier for Marketo is the “New Lead” trigger and the only actions available are “Create or Update Lead”, “Add Lead to List”, and “Find Lead”.

“New Lead” trigger for Marketo in Zapier
The 3 available Marketo actions in Zapier

This means if you want any of the other functionality offered through the Marketo REST API you will have to use the “Code by Zapier” app along with your own custom code in either Python (version 3.7) or Javascript (Node 10.x.x).

“Code by Zapier” action

N.B. Before importing any code into the “Code by Zapier” action I recommend testing the code in an online compiler e.g. OnlineGDB for Python, or in a platform such as Pycharm (for Python). Debugging errors within Zapier is not easy but if you use platforms such as these then you can leverage their tools for debugging and then copy and paste the code to Zapier once it is ready.

Adhering to Marketo REST API Limits

Once you start incorporating Marketo REST API calls into your scripts or Zapier actions it is possible for calls to be made in rapid succession using loops or for calls to be made in parallel using multi-threading or having multiple scripts running at once. In these scenarios, it is important to be aware of the Marketo REST API limits so that your requests do not get stopped for exceeding these limits.

50k Daily API Quota

If you are importing or exporting large amounts of data into or from Marketo, then it is advised to use the Bulk Import and Bulk Extract APIs, which are optimized for uploading or retrieving information and minimizing API Calls. If you are integrating Marketo with a business intelligence tool like Domo then you should ensure that this business intelligence tool is using the bulk extract API so it does not exhaust your daily API quota.

Rate Limit of 100 calls per 20 seconds

When making API calls within any sort of loop it is important to use a scheduler e.g. the apscheduler in Python, to throttle the number of requests being made.

If you are not concerned with how quickly your script runs then simply implementing a 0.2sec delay at the end of your loop will ensure that you do not exceed 100 calls per 20 seconds.

Concurrency Limit of 10 calls

Avoiding the concurrency limit comes down to scheduling and communication between the different scripts you have making requests to Marketo.

When performance is not a concern, then ensure that there is only one program making requests to Marketo at any point in time and that within this program the flow is linear so that the next API request will only commence once the previous API request has completed.

When performance is a concern and you need to have multiple programs running at once or multiple calls being made within a single program in parallel i.e. asynchronous programming, then these concurrent processes will need to communicate with one another and a scheduler library e.g. the apscheduler in Python should be used to ensure that no more than 10 calls are being made at once.

What can be automated with the Marketo API?

Now that you know where to find the Marketo API library and how to use these API requests in scripts or Zapier the world is your oyster! Go forth and API!

If you want examples of processes that you can automate using the Marketo API take a look at these posts for inspiration:


Tyron Pretorius

Automating with APIs, Python, Zapier, and Google Scripts 

Former engineer turned marketing operations lead who loves to get down and dirty with the Marketo API, Python, Zapier, and Google Scripts.

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