How to Debug and Test Variable Replacement in Your Requests?

This guide explains how to use a public “echo” service (for example: Postman Echo at
https://learning.postman.com/docs/developer/echo-api/) to design, test, and debug HTTP requests before you use them in External Data for Jira.

General Pattern

Real request (target system):

GET https://api.your-system.com/items?assignee=${issue.key}&status=${issue.fields.status.name}

Echo test version (temporary):

GET https://postman-echo.com/get?assignee=${issue.key}&status=${issue.fields.status.name}

Configure this echo version in your Field or Data Source, then test/simulate the response.
In the JSON response, check:

JSON

{
  "args": {
    "assignee": "PROJ-123",
    "status": "In Progress"
  },
  "url": "<https://postman-echo.com/get?assignee=PROJ-123&status=In%20Progress">
}

If the values match what you expect for that Jira issue, your variables are correct.
Then switch the base URL back to your real API.

Quick Workflow

Configure your request in External Data for Jira with variables.
Replace the base URL with https://postman-echo.com and adapt the path (/get, /post, etc.).
Trigger the request from the Data Source or Field Configuration window.
Inspect the echo response (args, url, headers, json) to see final resolved values.
Fix any variable names/placements.
Switch back to your real API base URL once everything looks correct.