# Build your first integration in 5 minutes

This walkthrough takes you from "no Wren account" to "first paid carbon offset via the API" in five minutes. We'll do it twice — once in **test mode** (safe, no charges) and once in **live mode** (real charge, real offset).

## 1. Sign up for an API team

Head to [wren.co/wren-api](https://www.wren.co/wren-api) and click **Get an API key**. The signup flow creates an API team — a shared workspace that owns the API token, the credit balance, and the billing relationship. Add a payment method when prompted (Stripe will only charge it when you top up credits or when an auto-refill triggers).

Once the team is created, head to [Settings → Team → API & Credits](https://www.wren.co/settings/team/api).

## 2. Generate your test token

Click **Generate test token**. The token format is `wren_test_<UUID>` — copy it and keep it handy.

Test tokens authenticate the team for sandbox requests: realistic canned responses, no charges, no real offsets, no notifications. Safe to share with teammates and embed in code samples.

## 3. Make your first sandbox call

POST `/api/offset-orders`  
The `"test": true` flag and `test_oo_` ID prefix confirm you hit the sandbox. Validation still ran — try omitting `tons` and you'll get a real `400`.

## 4. Top up real credits

Back in [API & Credits settings](https://www.wren.co/settings/team/api), enter an amount under **Add Credits** and confirm. Your team's payment method is charged once; the balance lands in the wallet.

We recommend starting with **$20** — covers roughly 0.85 tons of offset, enough to validate a couple of live calls before committing to higher volumes.

## 5. Make your first live call

Generate or reveal your live token (also on the API & Credits page) and swap the auth header:

No `"test": true` flag — that's a real offset. Hold onto the `id` (it's your `order_group_id`) — you can fetch the certificate at `GET /api/offset-orders/certificate/by-group/{id}`.

## What's next

- [Offset Orders](https://www.wren.co/docs/api/offset-orders) — full reference for `/api/offset-orders` (one-time, by-tonnage)
- [Project Orders](https://www.wren.co/docs/api/project-orders) — fund a specific project directly
- [Tree Orders](https://www.wren.co/docs/api/tree-orders) — plant trees instead of offsetting
- [Credits](https://www.wren.co/docs/api/credits) — wallet operations: balance, ledger, top-up, auto-refill
- [Portfolios](https://www.wren.co/docs/api/portfolios) — list of available portfolios with their projects

## Troubleshooting

**`401 Unauthorized` with a fresh token** — confirm you copied the full token (UUIDs are 36 chars; test tokens are `wren_test_` + 36). Whitespace inside the `Authorization` header is the most common culprit.

**`400` on a test call but the same call works live** — test mode runs the full validator. Check that `tons` is a number, `Content-Type: application/json` is set, and the body is valid JSON.

**Balance shows `$1,000.00` no matter what I do** — you're on a test token. Test mode is stateless: every request resets to the canned balance. Switch to your live token to see real balance changes.

**Live call returns `402 Insufficient credits`** — your team's credit balance is below the order cost. Top up at [API & Credits settings](https://www.wren.co/settings/team/api) or enable auto-refill.