diff --git a/package-lock.json b/package-lock.json
index a747260..f18f07d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -373,6 +373,7 @@
    "integrity": "sha512-HFN59MmQXGHVyYadKLVumYsA9dBFun/ldYxipEjzA4196jpLZd8UjEEBLkbEkvfYreDqJhZxYAWFPtrfhNpj4w==",
    "dev": true,
    "license": "MIT",
+   "peer": true,
    "dependencies": {
     "@babel/template": "^7.27.2",
     "@babel/types": "^7.28.4"
@@ -2024,6 +2025,7 @@
    "integrity": "sha512-LI9u/+laYG4Ds1TDKSJW2YPrIlcVYOwi2fUC6xB43lueCjgxV4lffOCZCtYFiH6TNOX+tQKXx97T4IKHbhyHEQ==",
    "dev": true,
    "license": "MIT",
+   "peer": true,
    "dependencies": {
     "@jridgewell/gen-mapping": "^0.3.5",
     "@jridgewell/trace-mapping": "^0.3.24"
@@ -2703,7 +2705,6 @@
    "resolved": "https://registry.npmjs.org/axios/-/axios-1.13.2.tgz",
    "integrity": "sha512-VPk9ebNqPcy5lRGuSlKx752IlDatOjT9paPlm8A7yOuW2Fbvp4X3JznJtT4f0GzGLLiWE9W8onz51SqLYwzGaA==",
    "license": "MIT",
-   "peer": true,
    "dependencies": {
     "follow-redirects": "^1.15.6",
     "form-data": "^4.0.4",
@@ -2831,7 +2832,6 @@
     }
    ],
    "license": "MIT",
-   "peer": true,
    "dependencies": {
     "baseline-browser-mapping": "^2.8.19",
     "caniuse-lite": "^1.0.30001751",
@@ -3085,7 +3085,8 @@
    "resolved": "https://registry.npmjs.org/convert-source-map/-/convert-source-map-2.0.0.tgz",
    "integrity": "sha512-Kvp459HrV2FEJ1CAsi1Ku+MY3kasH19TFykTz2xWmMeq6bk2NU3XXvfJ+Q61m0xktWwt+1HSYf3JZsTms3aRJg==",
    "dev": true,
-   "license": "MIT"
+   "license": "MIT",
+   "peer": true
   },
   "node_modules/core-js-compat": {
    "version": "3.46.0",
@@ -3541,6 +3542,7 @@
    "integrity": "sha512-3hN7NaskYvMDLQY55gnW3NQ+mesEAepTqlg+VEbj7zzqEMBVNhzcGYYeqFo/TlYz6eQiFcp1HcsCZO+nGgS8zg==",
    "dev": true,
    "license": "MIT",
+   "peer": true,
    "engines": {
     "node": ">=6.9.0"
    }
@@ -3937,6 +3939,7 @@
    "integrity": "sha512-XmOWe7eyHYH14cLdVPoyg+GOH3rYX++KpzrylJwSW98t3Nk+U8XOl8FWKOgwtzdb8lXGf6zYwDUzeHMWfxasyg==",
    "dev": true,
    "license": "MIT",
+   "peer": true,
    "bin": {
     "json5": "lib/cli.js"
    },
@@ -4277,7 +4280,6 @@
    "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
    "dev": true,
    "license": "MIT",
-   "peer": true,
    "engines": {
     "node": ">=12"
    },
@@ -4481,7 +4483,6 @@
    "integrity": "sha512-w8GmOxZfBmKknvdXU1sdM9NHcoQejwF/4mNgj2JuEEdRaHwwF12K7e9eXn1nLZ07ad+du76mkVsyeb2rKGllsA==",
    "dev": true,
    "license": "MIT",
-   "peer": true,
    "dependencies": {
     "@types/estree": "1.0.8"
    },
@@ -4858,8 +4859,7 @@
    "version": "2.8.1",
    "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
    "integrity": "sha512-oJFu94HQb+KVduSUQL7wnpmqnfmLsOA/nAh6b6EH0wCEoK0/mPeXU6c3wKDV83MkOuHPRHtSXKKU99IBazS/2w==",
-   "license": "0BSD",
-   "peer": true
+   "license": "0BSD"
   },
   "node_modules/tsx": {
    "version": "4.20.6",
@@ -4887,7 +4887,6 @@
    "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
    "dev": true,
    "license": "Apache-2.0",
-   "peer": true,
    "bin": {
     "tsc": "bin/tsc",
     "tsserver": "bin/tsserver"
diff --git a/src/ClientBuilder.js b/src/ClientBuilder.js
index 19a85b5..d4ae9d5 100644
--- a/src/ClientBuilder.js
+++ b/src/ClientBuilder.js
@@ -4,6 +4,7 @@ const BaseUrlSender = require("./BaseUrlSender");
 const AgentSender = require("./AgentSender");
 const StaticCredentials = require("./StaticCredentials");
 const SharedCredentials = require("./SharedCredentials");
+const BasicAuthCredentials = require("./BasicAuthCredentials");
 const CustomHeaderSender = require("./CustomHeaderSender");
 const StatusCodeSender = require("./StatusCodeSender");
 const LicenseSender = require("./LicenseSender");
@@ -54,7 +55,7 @@ class ClientBuilder {
 		this.customQueries = new Map();
 
 		function credentialsProvided() {
-			return signer instanceof StaticCredentials || signer instanceof SharedCredentials;
+			return signer instanceof StaticCredentials || signer instanceof SharedCredentials || signer instanceof BasicAuthCredentials;
 		}
 	}
 
diff --git a/src/SigningSender.ts b/src/SigningSender.ts
index ddb0701..7b4f936 100644
--- a/src/SigningSender.ts
+++ b/src/SigningSender.ts
@@ -1,5 +1,6 @@
 import { Request, Response, Sender } from "./types.js";
 import SharedCredentials from "./SharedCredentials.js";
+import BasicAuthCredentials from "./BasicAuthCredentials.js";
 import { UnprocessableEntityError } from "./Errors.js";
 
 interface Signer {
diff --git a/tests/test_SigningSender.ts b/tests/test_SigningSender.ts
index e594207..f4cef48 100644
--- a/tests/test_SigningSender.ts
+++ b/tests/test_SigningSender.ts
@@ -4,6 +4,7 @@ import Response from "../src/Response.js";
 import SigningSender from "../src/SigningSender.js";
 import StaticCredentials from "../src/StaticCredentials.js";
 import SharedCredentials from "../src/SharedCredentials.js";
+import BasicAuthCredentials from "../src/BasicAuthCredentials.js";
 import { UnprocessableEntityError } from "../src/Errors";
 
 describe("A signing sender", function () {
@@ -45,6 +46,16 @@ describe("A signing sender", function () {
 		);
 	});
 
+	it("signs a request with basic auth credentials.", function () {
+		const basicAuthCredentials = new BasicAuthCredentials(mockAuthId, mockAuthToken);
+		const signingSender = new SigningSender(mockSender, basicAuthCredentials);
+
+		signingSender.send(request);
+
+		expect("Authorization" in request.headers).to.equal(true);
+		expect((request.headers as Record<string, string>)["Authorization"]).to.include("Basic ");
+	});
+
 	it("errors if signing a POST request with shared credentials.", function () {
 		const sharedCredentials = new SharedCredentials(mockAuthId, mockHostName);
 		const signingSender = new SigningSender(mockSender, sharedCredentials);
@@ -55,4 +66,15 @@ describe("A signing sender", function () {
 
 		expect(() => signingSender.send(request)).to.throw(UnprocessableEntityError);
 	});
+
+	it("does not error if signing a POST request with basic auth credentials.", function () {
+		const basicAuthCredentials = new BasicAuthCredentials(mockAuthId, mockAuthToken);
+		const signingSender = new SigningSender(mockSender, basicAuthCredentials);
+		const mockRequestPayload = {
+			foo: "bar",
+		};
+		request.payload = mockRequestPayload;
+
+		expect(() => signingSender.send(request)).to.not.throw();
+	});
 });