diff --git a/README.md b/README.md
index f0fd17a915..2410b5b11a 100644
--- a/README.md
+++ b/README.md
@@ -79,6 +79,18 @@ yarn run lint
 
 ### Test
 
+Disable API tests OR define all required explorer API keys.
+
+```bash
+export DISABLE_API_TESTS=1
+# OR
+export EXPLORER_API_KEY_MAINNET=
+export EXPLORER_API_KEY_RINKEBY=
+export EXPLORER_API_KEY_FUSE=
+export EXPLORER_API_KEY_MATIC=
+export EXPLORER_API_KEY_FANTOM=
+```
+
 Test all the packages in the monorepo.
 
 ```bash
diff --git a/packages/payment-detection/README.md b/packages/payment-detection/README.md
index 60f039f3fe..63404465ef 100644
--- a/packages/payment-detection/README.md
+++ b/packages/payment-detection/README.md
@@ -64,3 +64,21 @@ The code generation is included in the pre-build script and can be run manually:
 ```
 yarn codegen
 ```
+
+# Test
+
+The ETH `InfoRetriever` tests require explorer API keys. Before running the
+payment-detection tests, define `DISABLE_API_TESTS` or define all required
+explorer API keys.
+
+```bash
+export DISABLE_API_TESTS=1
+# OR
+export EXPLORER_API_KEY_MAINNET=
+export EXPLORER_API_KEY_RINKEBY=
+export EXPLORER_API_KEY_FUSE=
+export EXPLORER_API_KEY_MATIC=
+export EXPLORER_API_KEY_FANTOM=
+
+yarn run test
+```
diff --git a/packages/payment-detection/test/eth/info-retriever.test.ts b/packages/payment-detection/test/eth/info-retriever.test.ts
index 635c5b4c09..c61fc98be8 100644
--- a/packages/payment-detection/test/eth/info-retriever.test.ts
+++ b/packages/payment-detection/test/eth/info-retriever.test.ts
@@ -45,7 +45,15 @@ describe('api/eth/info-retriever', () => {
     await expect(infoRetreiver.getTransferEvents()).rejects.toThrowError();
   });
 
-  describe('Multichain', () => {
+  // Utility for conditionally skipping tests
+  const describeIf = (
+    condition: any,
+    ...args: [string | number | Function | jest.FunctionLike, jest.EmptyFunction]
+  ) => (condition ? describe(...args) : describe.skip(...args));
+
+  // Skip tests if build is from external fork or API tests are disabled
+  // External forks cannot access secret API keys
+  describeIf(!process.env.CIRCLE_PR_NUMBER && !process.env.DISABLE_API_TESTS, 'Multichain', () => {
     // TODO temporary disable xDAI, CELO, Sokol, and Goerli
     // FIXME: API-based checks should run nightly and be mocked for CI
     [