Quickstart: 5‑Minute Echo API on MARS Engine

Build, deploy, and test your first endpoint without installing anything.

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1 . Prerequisites

You need	Why
A modern web browser (Chrome, Firefox, Edge, Safari)	MARS Engine runs entirely in‑browser.
A free MARS Engine account	Sign up at MARS Engine.

No local Node.js, Git, or database setup required.

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2 . Create a new project

1. Log in to the MARS Engine dashboard.
2. Click ➕ New Project → choose Blank → name it quickstart.
3. Wait a few seconds while the workspace spins up (you’ll land in the in‑browser IDE).

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3 . Add your first API script

1. In the File Explorer, click New File.
2. Enter the path api/echo and paste the code below:

// api/echo
/**
 * Simple echo endpoint.
 * GET /api/echo?msg=Hello
 */
const message = param('msg', 'Hello from MARS Engine!');
write('echo', message);

This script:

• Reads the msg parameter (param() helper).
• Writes a JSON key echo with the same value (write()).
• Runs inside an automatic DB transaction (no action needed here).

Click Save (Ctrl/Cmd + S).

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4 . Run & test

1. In the Run panel (top‑right), press ▶ Run.
   • The Browser opens a new tab which shows https://<workspace‑id>.mars-hosting.com.
2. Open a terminal and curl the endpoint (replace <workspace‑id>):

curl "https://<workspace-id>.mars-hosting.com/api/echo?msg=Hello"

You should see:

{ "echo": "Hello" }

or, without a query param:

curl https://<workspace-id>.mars-hosting.com/api/echo
# → { "echo": "Hello from MARS Engine!" }

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5 . What just happened?

Step	Behind the scenes
Request arrives	MARS Engine opens a DB transaction.
param()	Reads URL/body/file parameters.
write()	Buffers JSON response.
Script ends	Transaction auto‑commits and JSON is sent.

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6 . Next steps (≤30 min)

1. Add a database table → by using the Database module from the sidebar.
2. Query data with db.query('SELECT * FROM ...').
3. Make it realtime → add ws/chat.js with onMessage.
4. Generate a PDF using report.pdf() and stream it back.

See:

• Concepts/Request lifecycle – deep dive on transactions