diff --git a/src/Client.ts b/src/Client.ts
index 93779bb..75d8115 100644
--- a/src/Client.ts
+++ b/src/Client.ts
@@ -3,6 +3,7 @@ import type { Event } from './Event.js';
 import type { EventCandidate } from './EventCandidate.js';
 import type { EventType } from './EventType.js';
 import { isCloudEvent } from './isCloudEvent.js';
+import { isValidServerHeader } from './isValidServerHeader.js';
 import { readNdJsonStream } from './ndjson/readNdJsonStream.js';
 import type { ObserveEventsOptions } from './ObserveEventsOptions.js';
 import type { Precondition } from './Precondition.js';
@@ -49,6 +50,10 @@ class Client {
 			method: 'get',
 		});
 
+		if (!isValidServerHeader(response)) {
+			throw new Error('Server must be EventSourcingDB.');
+		}
+
 		if (response.status !== 200) {
 			throw new Error(`Failed to ping, got HTTP status code '${response.status}', expected '200'.`);
 		}
@@ -77,6 +82,10 @@ class Client {
 			},
 		});
 
+		if (!isValidServerHeader(response)) {
+			throw new Error('Server must be EventSourcingDB.');
+		}
+
 		if (response.status !== 200) {
 			throw new Error(
 				`Failed to verify API token, got HTTP status code '${response.status}', expected '200'.`,
@@ -115,6 +124,10 @@ class Client {
 			}),
 		});
 
+		if (!isValidServerHeader(response)) {
+			throw new Error('Server must be EventSourcingDB.');
+		}
+
 		if (response.status !== 200) {
 			throw new Error(
 				`Failed to write events, got HTTP status code '${response.status}', expected '200'.`,
@@ -174,6 +187,14 @@ class Client {
 					signal: combinedSignal,
 				});
 
+				if (!isValidServerHeader(response)) {
+					const serverHeader = response.headers.get('Server');
+					if (!serverHeader) {
+						throw new Error('Server must be EventSourcingDB, but Server header is missing.');
+					}
+					throw new Error(`Server must be EventSourcingDB, got Server header: '${serverHeader}'.`);
+				}
+
 				if (response.status !== 200) {
 					throw new Error(
 						`Failed to read events, got HTTP status code '${response.status}', expected '200'.`,
@@ -239,6 +260,14 @@ class Client {
 					signal: combinedSignal,
 				});
 
+				if (!isValidServerHeader(response)) {
+					const serverHeader = response.headers.get('Server');
+					if (!serverHeader) {
+						throw new Error('Server must be EventSourcingDB, but Server header is missing.');
+					}
+					throw new Error(`Server must be EventSourcingDB, got Server header: '${serverHeader}'.`);
+				}
+
 				if (response.status !== 200) {
 					throw new Error(
 						`Failed to run EventQL query, got HTTP status code '${response.status}', expected '200'.`,
@@ -314,6 +343,14 @@ class Client {
 					signal: combinedSignal,
 				});
 
+				if (!isValidServerHeader(response)) {
+					const serverHeader = response.headers.get('Server');
+					if (!serverHeader) {
+						throw new Error('Server must be EventSourcingDB, but Server header is missing.');
+					}
+					throw new Error(`Server must be EventSourcingDB, got Server header: '${serverHeader}'.`);
+				}
+
 				if (response.status !== 200) {
 					throw new Error(
 						`Failed to observe events, got HTTP status code '${response.status}', expected '200'.`,
@@ -371,6 +408,10 @@ class Client {
 			}),
 		});
 
+		if (!isValidServerHeader(response)) {
+			throw new Error('Server must be EventSourcingDB.');
+		}
+
 		if (response.status !== 200) {
 			throw new Error(
 				`Failed to register event schema, got HTTP status code '${response.status}', expected '200'.`,
@@ -411,6 +452,14 @@ class Client {
 					signal: combinedSignal,
 				});
 
+				if (!isValidServerHeader(response)) {
+					const serverHeader = response.headers.get('Server');
+					if (!serverHeader) {
+						throw new Error('Server must be EventSourcingDB, but Server header is missing.');
+					}
+					throw new Error(`Server must be EventSourcingDB, got Server header: '${serverHeader}'.`);
+				}
+
 				if (response.status !== 200) {
 					throw new Error(
 						`Failed to read subjects, got HTTP status code '${response.status}', expected '200'.`,
@@ -460,6 +509,10 @@ class Client {
 			}),
 		});
 
+		if (!isValidServerHeader(response)) {
+			throw new Error('Server must be EventSourcingDB.');
+		}
+
 		if (response.status !== 200) {
 			throw new Error(
 				`Failed to read event type, got HTTP status code '${response.status}', expected '200'.`,
@@ -504,6 +557,14 @@ class Client {
 					signal: combinedSignal,
 				});
 
+				if (!isValidServerHeader(response)) {
+					const serverHeader = response.headers.get('Server');
+					if (!serverHeader) {
+						throw new Error('Server must be EventSourcingDB, but Server header is missing.');
+					}
+					throw new Error(`Server must be EventSourcingDB, got Server header: '${serverHeader}'.`);
+				}
+
 				if (response.status !== 200) {
 					throw new Error(
 						`Failed to read event types, got HTTP status code '${response.status}', expected '200'.`,
diff --git a/src/isValidServerHeader.ts b/src/isValidServerHeader.ts
new file mode 100644
index 0000000..0130d25
--- /dev/null
+++ b/src/isValidServerHeader.ts
@@ -0,0 +1,15 @@
+const isValidServerHeader = (response: Response): boolean => {
+	const serverHeader = response.headers.get('Server');
+
+	if (!serverHeader) {
+		return false;
+	}
+
+	if (!serverHeader.startsWith('EventSourcingDB/')) {
+		return false;
+	}
+
+	return true;
+};
+
+export { isValidServerHeader };