Postman Setup

Import the official LMN Open API collection and make your first call in 2 minutes.

Overview

We publish two official Postman collections — one for sandbox, one for production. Each is pre-wired with endpoints, variables, descriptions, and example payloads. Import it once and you can click Send on any request without writing code.

Collection	File	Base URL	Key prefix
Sandbox	postman-sandbox.json	https://sandbox-api.lmnauto.com	lmn_stg_*
Production	postman-production.json	https://api.lmnauto.com	lmn_prd_*

Both collections share the same shape (same folders, same requests, same variable names). Only the default base_url and api_key differ. Most partners import both and keep them side by side — you work in sandbox during development and flip to production once certified.

The collections ship with these variables baked in:

Variable	Purpose
base_url	API host (pre-set per collection — do not change)
api_key	Your API key
vehicle_id	Sample ID for detail/order requests
order_id	Sample ID for order detail/cancel requests

Variable names use snake_case (base_url, api_key). A common mistake is defining them as baseUrl or x-api-key — these will resolve to empty strings and produce 404 or missing-key errors.

Production collection places real orders. Orders created via postman-production.json are binding bid commitments against live auction vehicles and will incur real charges. Always verify the collection name in Postman (look for “(Production)” vs “(Sandbox)” in the title) before clicking Send on any POST /v1/orders request.

Step 1 — Download the collections

Grab the collections here:

Sandbox Collection

postman/sandbox.json — safe to experiment, uses synthetic inventory

Production Collection

postman/production.json — live inventory and real orders

If you have questions during setup, contact [e-mail].

Step 2 — Import into Postman

1. Open Postman → File → Import (or drag the JSON file onto the sidebar).
2. Start with postman-sandbox.json. Confirm the import dialog — Postman creates a collection named LMN Open API (Sandbox).
3. Repeat for postman-production.json when you’re ready. It imports as a separate collection named LMN Open API (Production).
4. Expand either collection in the left sidebar. You should see folders for 0. Health, 1. Browse, 2. Order, and 3. Track & Fulfill.

The two collections are independent — editing one does not affect the other. Production has distinct api_key and base_url defaults so an accidentally copied request can’t hit the wrong environment.

Step 3 — Set your API key

Each collection ships with a placeholder key. Replace it with your real key per collection.

1. Open the sandbox collection variables

   Click the LMN Open API (Sandbox) collection in the sidebar → select the Variables tab.

2. Update the Current value column

   Locate the api_key row. Paste your sandbox key into the Current value column (not Initial value — Postman sends Current).

   Variable:      api_key
   Current value: lmn_stg_abc123...your_sandbox_key...
   
3. Save

   Press Cmd+S (macOS) or Ctrl+S (Windows). The variables persist locally.

4. Repeat for production (when ready)

   Open LMN Open API (Production) → Variables → paste your lmn_prd_* key into api_key Current value → Save.

Initial value vs Current value. Postman has two columns. Only Current value is used when sending requests. If you paste into Initial value, your requests will still send the placeholder and return 401 invalid_api_key.

Step 4 — Send your first request

1. In the sidebar, open Health → GET /v1/health.
2. Click Send.
3. Expected response:

{
  "status": "ok",
  "version": "1.0.0",
  "environment": "sandbox"
}

If you see this, authentication is not required for /v1/health but your base_url is correct. Now try Vehicles → GET /v1/vehicles — this uses the api_key variable.

Switching to production

Once your integration passes sandbox testing, open the LMN Open API (Production) collection (imported in Step 2). Its base_url is already set to https://api.lmnauto.com — the only thing you need to set is api_key (your lmn_prd_* key), as described in Step 3.

We deliberately ship two separate collections instead of one with a toggle. This prevents the most common integration accident: flipping an env var while testing and unknowingly placing a real order against live inventory. Keep sandbox and production in separate collections; name them clearly in the Postman sidebar.

Troubleshooting

Symptom	Cause	Fix
404 Site Not Found (HTML page with Roboto font)	base_url is empty or points to a misspelled Firebase host	Confirm base_url = https://sandbox-api.lmnauto.com — no trailing slash, no spaces
401 missing_api_key	x-api-key header not attached to the request	Official collection attaches it via the Authorization tab (type: API Key) — don’t remove it
401 invalid_api_key	Key/environment mismatch (stg key on prod URL or vice versa)	Check prefix: lmn_stg_* must go to sandbox-api.lmnauto.com
Empty response / connection reset	Custom domain SSL still provisioning	Takes up to 24 hours after DNS setup — retry later
Variable {{baseUrl}} shows as literal text	Variable name typo (camelCase vs snake_case)	Official collection uses {{base_url}}. If you see {{baseUrl}}, the request was modified — re-import or rename

Verifying with curl

If Postman behaves strangely, sanity-check with curl:

curl -i https://sandbox-api.lmnauto.com/v1/health
# Expect: HTTP/2 200 + {"status":"ok"...}

curl -i -H "x-api-key: lmn_stg_YOUR_KEY" \
  https://sandbox-api.lmnauto.com/v1/vehicles?limit=1
# Expect: HTTP/2 200 + {"data":[...]}

If curl works but Postman doesn’t, the issue is in your Postman configuration, not the API.

Opening the Postman Console

For deep debugging, enable the Postman Console (View → Show Postman Console or Cmd+Alt+C). Every Send prints the exact URL, headers, and body. Compare against the variable values to find substitution errors.

Next steps

• Full endpoint reference: Endpoints → Vehicles
• Error code matrix: Errors
• Webhook setup: Webhooks Overview