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How to build and host (for free!) a mock API from hardcoded data

In this example, we are going to build an API that serves data. This will then be hosted as a REST API. For this, we are going to be using RAW, a platform to quickly build and host APIs. To follow along, you will need an account, which you can create and use for free here if you don't have one already.

Let's get started!


If you are familiar with RAW and want to deploy this endpoint on your account, click below:

Mock API with hardcoded code
Find basketball players by identifier (mock data).

Sample usage:


For example, when called as /mock?id=1 the response is a JSON document such as:

"id": 1,
"name": "Stephen Curry",
"age": 34,
"championships": [2015, 2017, 2018, 2022]

... but when called with an unknown identifier, e.g. /mock?id=99, the response is an error such as:

Unknown identifier

Create a blank API endpoint in RAW

First, we should create a free account:

Once you login to RAW, you should head up to the 'Workspace' section as shown below.

Choose the workspace

Then, click on 'Add +' to create a new endpoint and choose a new 'Blank Endpoint' as shown below. You could also choose an existing template, but for this example, let's start blank and write the code ourselves.

Create blank endpoint

Write the endpoint code

Now that you have a blank endpoint, let's start writing some code. Before we start, here's an overview of the RAW Workspace.

Overview of the workspace

Now let's follow in steps:

Step 1: Write the code

In RAW, endpoints are written in Snapi, a simple-to-use programming language specifically created specifically for building APIs. You will see this is very simple to create.

Let's copy/paste the following code for our endpoint (see figure, as step '1'):

main(id: int) =
if (id == 1) then {id: 1, name: "Stephen Curry", age: 34, championships: [2015, 2017, 2018, 2022]}
else if (id == 2) then {id: 2, name: "LeBron James", age: 37, championships: [2012, 2013, 2016, 2020]}
else Error.Build("Unknown identifier")

// The following test will run if you press the play button.

Don't worry if you don't follow all the code just yet. This will be explained in detail below.

Step 2: Test the code

Next, let's test the code. Click on the play button (shown in the figure as step '2') and you will have a live preview of the result of calling the last line of the code.

Step 3: Choose the final URL

You can choose the exact path where your API will be hosted. This is shown in the figure as step '3'.

Step 4: Edit the metadata

Optionally, you can edit the metadata metadata (shown in the figure as step '4'). The metadata is important since RAW includes a built-in API Catalog that helps you and your users find API endpoints later.

Step 5: Deploy the endpoint live!

We are almost done. Now click to deploy your endpoint (shown in the figure as step '5').

Congratulations, your API is now published! It will be served right away and visible in the API Catalog as well.

How does the code work?

Let's look closer at how the Snapi code works!

main(id: int) =
if (id == 1) then
id: 1,
name: "Stephen Curry",
age: 34,
championships: [2015, 2017, 2018, 2022]
else if (id == 2) then
id: 2,
name: "LeBron James",
age: 37,
championships: [2012, 2013, 2016, 2020]
else Error.Build("Unknown identifier")

// The following test will run if you press the play button.
  • Line 1 defines the main method. Its arguments will become query parameters in the URL call. In this case, there's a single argument id, which is a number and is mandatory.
  • Lines 2, 9, 16 define the conditions based on the identifier passed.
  • The data is returned as part of each condition (e.g. Lines 3-8 and Lines 10-15). This uses Snapi records which are conceptually similar to JSON objects.
  • Line 16 uses Error.Build, to build an error response that is returned to the user, in case an unsupported identifier is passed. Refer to the error handling for more information.
  • Line 19 defines the test to run when the play button is pressed.

This is the simplest way to create a mock API as it allows you to quickly defined the desired output. However, it requires you to manually defined the data values in Snapi code. It is adequate for returning rather trivial responses.

For large volumes of data, this is not recommended however. In that scenario, prefer to use mock APIs that return data from existing data sources or, for a more complex solution, using code that dynamically generates data e.g. using Int.Range or Math.Random as the basic constructs.

Let's improve this API!

Now that you understand the basic concepts, there's many improvements that can be done. Below is a list of pointers:

What's next!

Take a look at other examples, or join us on Discord to learn more!

Ready to try it out?Register for free and start building today!

Otherwise, if you have questions/comments, join us on Discord!