eBay API

Navigate to developer.ebay.com and log in with your eBay account. Click My Account in the top navigation and select Application Keysets. If this is your first time, click Register a New Application and follow the registration wizard — you will need to provide an application name, a brief description, and the primary use case. Once registered, eBay generates three credential sets: Dev ID (identifies your developer account), App ID / Client ID (identifies your specific application — starts with YourName-AppName-PRD-... for production), and Cert ID / Client Secret (the secret used for token exchange). The App ID can be shared; the Cert ID must never be shared or placed in client code. Also note the Redirect URL (RuName) if you plan to implement the user authorization-code flow for the Sell/Fulfillment API — you configure this in the eBay developer portal under User Tokens → Get a Token from eBay via Your Application, where you register the redirect URL that eBay will send the authorization code to (this will be your Firebase Cloud Function's HTTPS trigger URL). For testing, also collect your Sandbox App ID and Sandbox Cert ID (separate credentials from production). Store all credentials securely — Cert IDs go into Firebase environment variables only.

Because the eBay OAuth token exchange requires your Cert ID (Client Secret), all token requests must run on the server. Create a Firebase Cloud Function named getEbayAppToken that implements the client credentials grant: it base64-encodes your AppID:CertID, POSTs to eBay's OAuth endpoint with grant_type=client_credentials and the required scopes, and returns the access token to FlutterFlow. Create a second function named startEbayUserAuth that generates the eBay authorization URL with your App ID, redirect URI, and requested scopes, then returns it to FlutterFlow — the app will open this URL in a WebView for the user to log in. Create a third function named exchangeEbayCode that receives the authorization code eBay sends after user consent, exchanges it for an access token and refresh token using the authorization_code grant, stores the refresh token securely (in Firestore under the user's document), and returns the access token to FlutterFlow. Create a fourth function named refreshEbayToken that reads the stored refresh token and mints a fresh access token when the current one expires (eBay user tokens typically last 2 hours). Set EBAY_APP_ID, EBAY_CERT_ID, and EBAY_REDIRECT_URI as Firebase environment variables before deploying.

1// Firebase Cloud Function: index.js (simplified)
2const functions = require('firebase-functions');
3const fetch = require('node-fetch');
4const admin = require('firebase-admin');
5admin.initializeApp();
6
7const EBAY_OAUTH_URL = 'https://api.ebay.com/identity/v1/oauth2/token';
8// Use https://api.sandbox.ebay.com/identity/v1/oauth2/token for sandbox
9
10// 1. Application token (Browse API - no user login needed)
11exports.getEbayAppToken = functions.https.onCall(async (data, context) => {
12  const appId = process.env.EBAY_APP_ID;
13  const certId = process.env.EBAY_CERT_ID;
14  const credentials = Buffer.from(`${appId}:${certId}`).toString('base64');
15
16  const response = await fetch(EBAY_OAUTH_URL, {
17    method: 'POST',
18    headers: {
19      'Authorization': `Basic ${credentials}`,
20      'Content-Type': 'application/x-www-form-urlencoded',
21    },
22    body: 'grant_type=client_credentials&scope=https%3A%2F%2Fapi.ebay.com%2Foauth%2Fapi_scope',
23  });
24  const token = await response.json();
25  return { accessToken: token.access_token, expiresIn: token.expires_in };
26});
27
28// 2. Exchange authorization code for user token
29exports.exchangeEbayCode = functions.https.onCall(async (data, context) => {
30  if (!context.auth) throw new functions.https.HttpsError('unauthenticated', 'Login required');
31
32  const { code } = data;
33  const appId = process.env.EBAY_APP_ID;
34  const certId = process.env.EBAY_CERT_ID;
35  const redirectUri = process.env.EBAY_REDIRECT_URI;
36  const credentials = Buffer.from(`${appId}:${certId}`).toString('base64');
37
38  const response = await fetch(EBAY_OAUTH_URL, {
39    method: 'POST',
40    headers: {
41      'Authorization': `Basic ${credentials}`,
42      'Content-Type': 'application/x-www-form-urlencoded',
43    },
44    body: `grant_type=authorization_code&code=${encodeURIComponent(code)}&redirect_uri=${encodeURIComponent(redirectUri)}`,
45  });
46  const token = await response.json();
47
48  // Store refresh token securely in Firestore
49  await admin.firestore().collection('ebay_tokens').doc(context.auth.uid).set({
50    refreshToken: token.refresh_token,
51    updatedAt: admin.firestore.FieldValue.serverTimestamp(),
52  });
53
54  return { accessToken: token.access_token, expiresIn: token.expires_in };
55});

With application token handling in place, build the product search flow in FlutterFlow. First, add an On App Load action on your home page that calls the getEbayAppToken Cloud Function and stores the returned accessToken in an App State variable named ebayAppToken. Create an API Group named eBayBrowse with base URL https://api.ebay.com. Add a header Authorization with the value Bearer {{accessToken}} and a variable ebayAccessToken — at runtime, set this to FFAppState().ebayAppToken. Create an API Call named SearchItems with Method GET and URL Path /buy/browse/v1/item_summary/search. Add query variables: q (search keyword), limit (integer, default 20), offset (integer, default 0), and filter (string, optional — e.g., conditions:{NEW} for new items only). The full URL path becomes /buy/browse/v1/item_summary/search?q={{q}}&limit={{limit}}&offset={{offset}}. In the Response & Test tab, click Test after entering a sample keyword (e.g., 'laptop'). Generate JSON Paths from the response. Look for $.itemSummaries[*].itemId, $.itemSummaries[*].title, $.itemSummaries[*].price.value, $.itemSummaries[*].image.imageUrl, $.itemSummaries[*].condition, and $.total. In your FlutterFlow canvas, add a SearchBar widget and a ListView. Bind the SearchBar's on-submit action to call SearchItems with the search text and display results in the ListView.

1// eBay Browse API JSON paths
2// For GET /buy/browse/v1/item_summary/search response
3
4$.total                              → totalResults
5$.itemSummaries[*].itemId            → itemId
6$.itemSummaries[*].title             → itemTitle
7$.itemSummaries[*].price.value       → itemPrice
8$.itemSummaries[*].price.currency    → currency
9$.itemSummaries[*].image.imageUrl    → imageUrl
10$.itemSummaries[*].condition         → condition
11$.itemSummaries[*].itemWebUrl        → ebayListingUrl
12$.itemSummaries[*].seller.username   → sellerName
13$.itemSummaries[*].shippingOptions[0].shippingCost.value → shippingCost

Seller features (viewing orders, updating listings, tracking fulfillment) require a user token obtained through the full OAuth authorization-code flow. This involves the user seeing an eBay login page, approving your app's requested permissions, and eBay redirecting back to your Cloud Function with an authorization code. In FlutterFlow, on the seller dashboard screen, add a Connect eBay Account button. Its action should call a Firebase Cloud Function (or construct the URL directly in FlutterFlow) that returns the eBay authorization URL — it looks like https://auth.ebay.com/oauth2/authorize?client_id={your_app_id}&redirect_uri={your_redirect_uri}&response_type=code&scope={scopes}. Open this URL in FlutterFlow's in-app WebView widget (navigate to it via the Launch URL action or an embedded WebView widget on the page). The user logs in to eBay and approves the permissions. eBay redirects to your configured Redirect URI, which should be your exchangeEbayCode Cloud Function's HTTPS trigger URL. The Cloud Function extracts the code parameter from the redirect, exchanges it for an access token and refresh token, stores the refresh token in Firestore, and redirects the browser to a success page (or you can detect the redirect URL change in the WebView and close it). Store the returned access token in App State as ebayUserToken. All Sell/Fulfillment API calls use this token.

1// eBay Authorization URL construction
2// Build this in your Cloud Function or FlutterFlow and open in WebView
3
4const authUrl = [
5  'https://auth.ebay.com/oauth2/authorize',
6  '?client_id=', encodeURIComponent(process.env.EBAY_APP_ID),
7  '&redirect_uri=', encodeURIComponent(process.env.EBAY_REDIRECT_URI),
8  '&response_type=code',
9  // Scopes: sell.fulfillment = order management, sell.inventory = listings
10  '&scope=', encodeURIComponent(
11    'https://api.ebay.com/oauth/api_scope ' +
12    'https://api.ebay.com/oauth/api_scope/sell.fulfillment ' +
13    'https://api.ebay.com/oauth/api_scope/sell.inventory'
14  ),
15  '&state=flutterflow-auth-request', // pass-through to verify callback
16].join('');
17
18// For sandbox testing, use:
19// https://auth.sandbox.ebay.com/oauth2/authorize
20// and sandbox App ID/redirect URI

With the user access token stored in App State, create a second API Group named eBaySell with base URL https://api.ebay.com and the same Bearer authorization header pattern, this time using FFAppState().ebayUserToken. Add an API Call named GetOrders with Method GET and URL Path /sell/fulfillment/v1/order. This endpoint returns the seller's eBay orders including buyer details, items, payment status, and fulfillment state. Map JSON paths like $.orders[*].orderId, $.orders[*].buyer.username, $.orders[*].totalFeeBasisAmount.value, $.orders[*].orderPaymentStatus, and $.orders[*].lineItems[0].title to display in a ListView. eBay user tokens expire after approximately 2 hours. To handle token refresh gracefully, store the token expiry timestamp in App State alongside the token. At the top of any action that calls the Sell API, add a Conditional Check: if the current time is within 5 minutes of the expiry time, call the refreshEbayToken Cloud Function first, update the App State token and expiry, then proceed with the API call. This prevents mid-session 401 errors from surprising the user.

1// eBay Sell Fulfillment API JSON paths
2// For GET /sell/fulfillment/v1/order response
3
4$.orders[*].orderId                       → orderId
5$.orders[*].buyer.username                → buyerUsername
6$.orders[*].creationDate                  → orderDate
7$.orders[*].orderPaymentStatus            → paymentStatus
8$.orders[*].fulfillmentStartInstructions[0].shippingStep.shipTo.fullName → shipToName
9$.orders[*].lineItems[0].title            → itemTitle
10$.orders[*].lineItems[0].quantity         → quantity
11$.orders[*].totalFeeBasisAmount.value     → orderTotal
12$.orders[*].totalFeeBasisAmount.currency  → currency
13
14// Token expiry check pseudocode for Action Flow Editor:
15// IF DateTime.now() >= FFAppState().ebayTokenExpiry - 5 minutes
16//   THEN call refreshEbayToken Cloud Function
17//   UPDATE ebayUserToken and ebayTokenExpiry in App State
18// THEN call GetOrders API