diff --git a/test/test.certificate-provision.ts b/test/test.certificate-provision.ts
new file mode 100644
index 0000000..33fec90
--- /dev/null
+++ b/test/test.certificate-provision.ts
@@ -0,0 +1,350 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import { SmartProxy } from '../ts/index.js';
+import type { TSmartProxyCertProvisionObject } from '../ts/index.js';
+import * as fs from 'fs';
+import * as path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+let testProxy: SmartProxy;
+
+// Load test certificates from helpers
+const testCert = fs.readFileSync(path.join(__dirname, 'helpers/test-cert.pem'), 'utf8');
+const testKey = fs.readFileSync(path.join(__dirname, 'helpers/test-key.pem'), 'utf8');
+
+tap.test('SmartProxy should support custom certificate provision function', async () => {
+  // Create test certificate object - the type is from plugins.tsclass.network.ICert
+  // but we return a simple object with the required properties
+  const testCertObject = {
+    cert: testCert,
+    key: testKey,
+    ca: ''
+  };
+  
+  // Custom certificate store for testing
+  const customCerts = new Map<string, typeof testCertObject>();
+  customCerts.set('test.example.com', testCertObject);
+  
+  // Create proxy with custom certificate provision
+  testProxy = new SmartProxy({
+    certProvisionFunction: async (domain: string): Promise<TSmartProxyCertProvisionObject> => {
+      console.log(`Custom cert provision called for domain: ${domain}`);
+      
+      // Return custom cert for known domains
+      if (customCerts.has(domain)) {
+        console.log(`Returning custom certificate for ${domain}`);
+        return customCerts.get(domain)! as unknown as TSmartProxyCertProvisionObject;
+      }
+      
+      // Fallback to Let's Encrypt for other domains
+      console.log(`Falling back to Let's Encrypt for ${domain}`);
+      return 'http01';
+    },
+    certProvisionFallbackToAcme: true,
+    acme: {
+      email: 'test@example.com',
+      useProduction: false
+    },
+    routes: [
+      {
+        name: 'test-route',
+        match: {
+          ports: [443],
+          domains: ['test.example.com']
+        },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 8080
+          },
+          tls: {
+            mode: 'terminate',
+            certificate: 'auto'
+          }
+        }
+      }
+    ]
+  });
+  
+  expect(testProxy).toBeInstanceOf(SmartProxy);
+});
+
+tap.test('Custom certificate provision function should be called', async () => {
+  let provisionCalled = false;
+  const provisionedDomains: string[] = [];
+  
+  const testProxy2 = new SmartProxy({
+    certProvisionFunction: async (domain: string): Promise<TSmartProxyCertProvisionObject> => {
+      provisionCalled = true;
+      provisionedDomains.push(domain);
+      
+      // Return a test certificate using the loaded files
+      // We need to return a proper cert object that satisfies the type
+      return {
+        cert: testCert,
+        key: testKey,
+        ca: ''
+      } as unknown as TSmartProxyCertProvisionObject;
+    },
+    acme: {
+      email: 'test@example.com',
+      useProduction: false,
+      port: 9080
+    },
+    routes: [
+      {
+        name: 'custom-cert-route',
+        match: {
+          ports: [9443],
+          domains: ['custom.example.com']
+        },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 8080
+          },
+          tls: {
+            mode: 'terminate',
+            certificate: 'auto'
+          }
+        }
+      }
+    ]
+  });
+  
+  // Mock the certificate manager to test our custom provision function
+  let certManagerCalled = false;
+  const origCreateCertManager = (testProxy2 as any).createCertificateManager;
+  (testProxy2 as any).createCertificateManager = async function(...args: any[]) {
+    const certManager = await origCreateCertManager.apply(testProxy2, args);
+    
+    // Override provisionAllCertificates to track calls
+    const origProvisionAll = certManager.provisionAllCertificates;
+    certManager.provisionAllCertificates = async function() {
+      certManagerCalled = true;
+      await origProvisionAll.call(certManager);
+    };
+    
+    return certManager;
+  };
+  
+  // Start the proxy (this will trigger certificate provisioning)
+  await testProxy2.start();
+  
+  expect(certManagerCalled).toBeTrue();
+  expect(provisionCalled).toBeTrue();
+  expect(provisionedDomains).toContain('custom.example.com');
+  
+  await testProxy2.stop();
+});
+
+tap.test('Should fallback to ACME when custom provision fails', async () => {
+  const failedDomains: string[] = [];
+  let acmeAttempted = false;
+  
+  const testProxy3 = new SmartProxy({
+    certProvisionFunction: async (domain: string): Promise<TSmartProxyCertProvisionObject> => {
+      failedDomains.push(domain);
+      throw new Error('Custom provision failed for testing');
+    },
+    certProvisionFallbackToAcme: true,
+    acme: {
+      email: 'test@example.com',
+      useProduction: false,
+      port: 9080
+    },
+    routes: [
+      {
+        name: 'fallback-route',
+        match: {
+          ports: [9444],
+          domains: ['fallback.example.com']
+        },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 8080
+          },
+          tls: {
+            mode: 'terminate',
+            certificate: 'auto'
+          }
+        }
+      }
+    ]
+  });
+  
+  // Mock to track ACME attempts
+  const origCreateCertManager = (testProxy3 as any).createCertificateManager;
+  (testProxy3 as any).createCertificateManager = async function(...args: any[]) {
+    const certManager = await origCreateCertManager.apply(testProxy3, args);
+    
+    // Mock SmartAcme to avoid real ACME calls
+    (certManager as any).smartAcme = {
+      getCertificateForDomain: async () => {
+        acmeAttempted = true;
+        throw new Error('Mocked ACME failure');
+      }
+    };
+    
+    return certManager;
+  };
+  
+  // Start the proxy
+  await testProxy3.start();
+  
+  // Custom provision should have failed
+  expect(failedDomains).toContain('fallback.example.com');
+  
+  // ACME should have been attempted as fallback
+  expect(acmeAttempted).toBeTrue();
+  
+  await testProxy3.stop();
+});
+
+tap.test('Should not fallback when certProvisionFallbackToAcme is false', async () => {
+  let errorThrown = false;
+  let errorMessage = '';
+  
+  const testProxy4 = new SmartProxy({
+    certProvisionFunction: async (_domain: string): Promise<TSmartProxyCertProvisionObject> => {
+      throw new Error('Custom provision failed for testing');
+    },
+    certProvisionFallbackToAcme: false,
+    routes: [
+      {
+        name: 'no-fallback-route',
+        match: {
+          ports: [9445],
+          domains: ['no-fallback.example.com']
+        },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 8080
+          },
+          tls: {
+            mode: 'terminate',
+            certificate: 'auto'
+          }
+        }
+      }
+    ]
+  });
+  
+  // Mock certificate manager to capture errors
+  const origCreateCertManager = (testProxy4 as any).createCertificateManager;
+  (testProxy4 as any).createCertificateManager = async function(...args: any[]) {
+    const certManager = await origCreateCertManager.apply(testProxy4, args);
+    
+    // Override provisionAllCertificates to capture errors
+    const origProvisionAll = certManager.provisionAllCertificates;
+    certManager.provisionAllCertificates = async function() {
+      try {
+        await origProvisionAll.call(certManager);
+      } catch (e) {
+        errorThrown = true;
+        errorMessage = e.message;
+        throw e;
+      }
+    };
+    
+    return certManager;
+  };
+  
+  try {
+    await testProxy4.start();
+  } catch (e) {
+    // Expected to fail
+  }
+  
+  expect(errorThrown).toBeTrue();
+  expect(errorMessage).toInclude('Custom provision failed for testing');
+  
+  await testProxy4.stop();
+});
+
+tap.test('Should return http01 for unknown domains', async () => {
+  let returnedHttp01 = false;
+  let acmeAttempted = false;
+  
+  const testProxy5 = new SmartProxy({
+    certProvisionFunction: async (domain: string): Promise<TSmartProxyCertProvisionObject> => {
+      if (domain === 'known.example.com') {
+        return {
+          cert: testCert,
+          key: testKey,
+          ca: ''
+        } as unknown as TSmartProxyCertProvisionObject;
+      }
+      returnedHttp01 = true;
+      return 'http01';
+    },
+    acme: {
+      email: 'test@example.com',
+      useProduction: false,
+      port: 9081
+    },
+    routes: [
+      {
+        name: 'unknown-domain-route',
+        match: {
+          ports: [9446],
+          domains: ['unknown.example.com']
+        },
+        action: {
+          type: 'forward',
+          target: {
+            host: 'localhost',
+            port: 8080
+          },
+          tls: {
+            mode: 'terminate',
+            certificate: 'auto'
+          }
+        }
+      }
+    ]
+  });
+  
+  // Mock to track ACME attempts
+  const origCreateCertManager = (testProxy5 as any).createCertificateManager;
+  (testProxy5 as any).createCertificateManager = async function(...args: any[]) {
+    const certManager = await origCreateCertManager.apply(testProxy5, args);
+    
+    // Mock SmartAcme to track attempts
+    (certManager as any).smartAcme = {
+      getCertificateForDomain: async () => {
+        acmeAttempted = true;
+        throw new Error('Mocked ACME failure');
+      }
+    };
+    
+    return certManager;
+  };
+  
+  await testProxy5.start();
+  
+  // Should have returned http01 for unknown domain
+  expect(returnedHttp01).toBeTrue();
+  
+  // ACME should have been attempted
+  expect(acmeAttempted).toBeTrue();
+  
+  await testProxy5.stop();
+});
+
+tap.test('cleanup', async () => {
+  // Clean up any test proxies
+  if (testProxy) {
+    await testProxy.stop();
+  }
+});
+
+export default tap.start();
\ No newline at end of file
diff --git a/ts/proxies/smart-proxy/certificate-manager.ts b/ts/proxies/smart-proxy/certificate-manager.ts
index eb20c3b..3eac595 100644
--- a/ts/proxies/smart-proxy/certificate-manager.ts
+++ b/ts/proxies/smart-proxy/certificate-manager.ts
@@ -12,7 +12,7 @@ export interface ICertStatus {
   status: 'valid' | 'pending' | 'expired' | 'error';
   expiryDate?: Date;
   issueDate?: Date;
-  source: 'static' | 'acme';
+  source: 'static' | 'acme' | 'custom';
   error?: string;
 }
 
@@ -22,6 +22,7 @@ export interface ICertificateData {
   ca?: string;
   expiryDate: Date;
   issueDate: Date;
+  source?: 'static' | 'acme' | 'custom';
 }
 
 export class SmartCertManager {
@@ -50,6 +51,12 @@ export class SmartCertManager {
   // ACME state manager reference
   private acmeStateManager: AcmeStateManager | null = null;
   
+  // Custom certificate provision function
+  private certProvisionFunction?: (domain: string) => Promise<plugins.tsclass.network.ICert | 'http01'>;
+  
+  // Whether to fallback to ACME if custom provision fails
+  private certProvisionFallbackToAcme: boolean = true;
+  
   constructor(
     private routes: IRouteConfig[],
     private certDir: string = './certs',
@@ -89,6 +96,20 @@ export class SmartCertManager {
     this.globalAcmeDefaults = defaults;
   }
   
+  /**
+   * Set custom certificate provision function
+   */
+  public setCertProvisionFunction(fn: (domain: string) => Promise<plugins.tsclass.network.ICert | 'http01'>): void {
+    this.certProvisionFunction = fn;
+  }
+  
+  /**
+   * Set whether to fallback to ACME if custom provision fails
+   */
+  public setCertProvisionFallbackToAcme(fallback: boolean): void {
+    this.certProvisionFallbackToAcme = fallback;
+  }
+  
   /**
    * Set callback for updating routes (used for challenge routes)
    */
@@ -212,15 +233,6 @@ export class SmartCertManager {
     route: IRouteConfig, 
     domains: string[]
   ): Promise<void> {
-    if (!this.smartAcme) {
-      throw new Error(
-        'SmartAcme not initialized. This usually means no ACME email was provided. ' +
-        'Please ensure you have configured ACME with an email address either:\n' +
-        '1. In the top-level "acme" configuration\n' +
-        '2. In the route\'s "tls.acme" configuration'
-      );
-    }
-    
     const primaryDomain = domains[0];
     const routeName = route.name || primaryDomain;
     
@@ -229,10 +241,68 @@ export class SmartCertManager {
     if (existingCert && this.isCertificateValid(existingCert)) {
       logger.log('info', `Using existing valid certificate for ${primaryDomain}`, { domain: primaryDomain, component: 'certificate-manager' });
       await this.applyCertificate(primaryDomain, existingCert);
-      this.updateCertStatus(routeName, 'valid', 'acme', existingCert);
+      this.updateCertStatus(routeName, 'valid', existingCert.source || 'acme', existingCert);
       return;
     }
     
+    // Check for custom provision function first
+    if (this.certProvisionFunction) {
+      try {
+        logger.log('info', `Attempting custom certificate provision for ${primaryDomain}`, { domain: primaryDomain, component: 'certificate-manager' });
+        const result = await this.certProvisionFunction(primaryDomain);
+        
+        if (result === 'http01') {
+          logger.log('info', `Custom function returned 'http01', falling back to Let's Encrypt for ${primaryDomain}`, { domain: primaryDomain, component: 'certificate-manager' });
+          // Continue with existing ACME logic below
+        } else {
+          // Use custom certificate
+          const customCert = result as plugins.tsclass.network.ICert;
+          
+          // Convert to internal certificate format
+          const certData: ICertificateData = {
+            cert: customCert.cert,
+            key: customCert.key,
+            ca: customCert.ca || '',
+            issueDate: new Date(),
+            expiryDate: this.extractExpiryDate(customCert.cert),
+            source: 'custom'
+          };
+          
+          // Store and apply certificate
+          await this.certStore.saveCertificate(routeName, certData);
+          await this.applyCertificate(primaryDomain, certData);
+          this.updateCertStatus(routeName, 'valid', 'custom', certData);
+          
+          logger.log('info', `Custom certificate applied for ${primaryDomain}`, { 
+            domain: primaryDomain,
+            expiryDate: certData.expiryDate,
+            component: 'certificate-manager'
+          });
+          return;
+        }
+      } catch (error) {
+        logger.log('error', `Custom cert provision failed for ${primaryDomain}: ${error.message}`, {
+          domain: primaryDomain,
+          error: error.message,
+          component: 'certificate-manager'
+        });
+        // Check if we should fallback to ACME
+        if (!this.certProvisionFallbackToAcme) {
+          throw error;
+        }
+        logger.log('info', `Falling back to Let's Encrypt for ${primaryDomain}`, { domain: primaryDomain, component: 'certificate-manager' });
+      }
+    }
+    
+    if (!this.smartAcme) {
+      throw new Error(
+        'SmartAcme not initialized. This usually means no ACME email was provided. ' +
+        'Please ensure you have configured ACME with an email address either:\n' +
+        '1. In the top-level "acme" configuration\n' +
+        '2. In the route\'s "tls.acme" configuration'
+      );
+    }
+    
     // Apply renewal threshold from global defaults or route config
     const renewThreshold = route.action.tls?.acme?.renewBeforeDays || 
                          this.globalAcmeDefaults?.renewThresholdDays || 
@@ -280,7 +350,8 @@ export class SmartCertManager {
         key: cert.privateKey, 
         ca: cert.publicKey, // Use same as cert for now
         expiryDate: new Date(cert.validUntil),
-        issueDate: new Date(cert.created)
+        issueDate: new Date(cert.created),
+        source: 'acme'
       };
       
       await this.certStore.saveCertificate(routeName, certData);
@@ -328,7 +399,8 @@ export class SmartCertManager {
         cert,
         key,
         expiryDate: certInfo.validTo,
-        issueDate: certInfo.validFrom
+        issueDate: certInfo.validFrom,
+        source: 'static'
       };
       
       // Save to store for consistency
@@ -399,6 +471,19 @@ export class SmartCertManager {
     return cert.expiryDate > expiryThreshold;
   }
   
+  /**
+   * Extract expiry date from a PEM certificate
+   */
+  private extractExpiryDate(_certPem: string): Date {
+    // For now, we'll default to 90 days for custom certificates
+    // In production, you might want to use a proper X.509 parser
+    // or require the custom cert provider to include expiry info
+    logger.log('info', 'Using default 90-day expiry for custom certificate', {
+      component: 'certificate-manager'
+    });
+    return new Date(Date.now() + 90 * 24 * 60 * 60 * 1000);
+  }
+  
   
   /**
    * Add challenge route to SmartProxy
diff --git a/ts/proxies/smart-proxy/models/interfaces.ts b/ts/proxies/smart-proxy/models/interfaces.ts
index 6464728..e98a2e8 100644
--- a/ts/proxies/smart-proxy/models/interfaces.ts
+++ b/ts/proxies/smart-proxy/models/interfaces.ts
@@ -135,6 +135,12 @@ export interface ISmartProxyOptions {
    * or a static certificate object for immediate provisioning.
    */
   certProvisionFunction?: (domain: string) => Promise<TSmartProxyCertProvisionObject>;
+  
+  /**
+   * Whether to fallback to ACME if custom certificate provision fails.
+   * Default: true
+   */
+  certProvisionFallbackToAcme?: boolean;
 }
 
 /**
diff --git a/ts/proxies/smart-proxy/smart-proxy.ts b/ts/proxies/smart-proxy/smart-proxy.ts
index e4d375d..afe5ff3 100644
--- a/ts/proxies/smart-proxy/smart-proxy.ts
+++ b/ts/proxies/smart-proxy/smart-proxy.ts
@@ -243,6 +243,16 @@ export class SmartProxy extends plugins.EventEmitter {
       certManager.setGlobalAcmeDefaults(this.settings.acme);
     }
     
+    // Pass down the custom certificate provision function if available
+    if (this.settings.certProvisionFunction) {
+      certManager.setCertProvisionFunction(this.settings.certProvisionFunction);
+    }
+    
+    // Pass down the fallback to ACME setting
+    if (this.settings.certProvisionFallbackToAcme !== undefined) {
+      certManager.setCertProvisionFallbackToAcme(this.settings.certProvisionFallbackToAcme);
+    }
+    
     await certManager.initialize();
     return certManager;
   }