diff --git a/src/api/auth.c b/src/api/auth.c
index e0a4698b..aa8fb9af 100644
--- a/src/api/auth.c
+++ b/src/api/auth.c
@@ -509,7 +509,8 @@ int api_auth(struct ftl_conn *api)
 	// else: Login attempt
 	// - Client tries to authenticate using a password, or
 	// - There no password on this machine
-	if(empty_password ? true : verify_password(password, config.webserver.api.pwhash.v.s))
+	const enum password_result result = empty_password ? true : verify_password(password, config.webserver.api.pwhash.v.s, true);
+	if(result == PASSWORD_CORRECT)
 	{
 		// Accepted
 
@@ -604,6 +605,14 @@ int api_auth(struct ftl_conn *api)
 			log_warn("No free API seats available, not authenticating client");
 		}
 	}
+	else if(result == PASSWORD_RATE_LIMITED)
+	{
+		// Rate limited
+		return send_json_error(api, 429,
+					"too_many_requests",
+					"Too many requests",
+					"login rate limiting");
+	}
 	else
 	{
 		log_debug(DEBUG_API, "API: Password incorrect: '%s'", password);
diff --git a/src/api/config.c b/src/api/config.c
index b9daf616..6f3fa21b 100644
--- a/src/api/config.c
+++ b/src/api/config.c
@@ -287,7 +287,7 @@ static const char *getJSONvalue(struct conf_item *conf_item, cJSON *elem, struct
 			char *pwhash = strlen(elem->valuestring) > 0 ? create_password(elem->valuestring) : strdup("");
 
 			// Verify that the password hash is valid
-			if(!verify_password(elem->valuestring, pwhash))
+			if(verify_password(elem->valuestring, pwhash, false) != PASSWORD_CORRECT)
 			{
 				free(pwhash);
 				return "Failed to create password hash (verification failed), password remains unchanged";
diff --git a/src/api/docs/content/specs/auth.yaml b/src/api/docs/content/specs/auth.yaml
index f46645fb..2c314181 100644
--- a/src/api/docs/content/specs/auth.yaml
+++ b/src/api/docs/content/specs/auth.yaml
@@ -79,6 +79,14 @@ components:
                   allOf:
                     - $ref: 'common.yaml#/components/errors/unauthorized'
                     - $ref: 'common.yaml#/components/schemas/took'
+          '429':
+            description: Too Many Requests
+            content:
+              application/json:
+                schema:
+                  allOf:
+                    - $ref: 'common.yaml#/components/errors/too_many_requests'
+                    - $ref: 'common.yaml#/components/schemas/took'
       delete:
         summary: Delete session
         tags:
diff --git a/src/api/docs/content/specs/common.yaml b/src/api/docs/content/specs/common.yaml
index 75129d23..fa82c83c 100644
--- a/src/api/docs/content/specs/common.yaml
+++ b/src/api/docs/content/specs/common.yaml
@@ -53,6 +53,26 @@ components:
               nullable: true
               description: "No additional data available"
               example: null
+    too_many_requests:
+      type: object
+      description: "Too many requests (rate limiting)"
+      properties:
+        error:
+          type: object
+          properties:
+            key:
+              type: string
+              description: "Machine-readable error type"
+              example: "too_many_requests"
+            message:
+              type: string
+              description: "Human-readable error message"
+              example: "Too many requests"
+            hint:
+              type: string
+              nullable: true
+              description: "No additional data available"
+              example: null
   headers:
     Location:
       description: Location of created resource
diff --git a/src/args.c b/src/args.c
index 3f90d761..877b0bc9 100644
--- a/src/args.c
+++ b/src/args.c
@@ -58,6 +58,8 @@
 #include "tools/dhcp-discover.h"
 // run_arp_scan()
 #include "tools/arp-scan.h"
+// run_performance_test()
+#include "config/password.h"
 
 // defined in dnsmasq.c
 extern void print_dnsmasq_version(const char *yellow, const char *green, const char *bold, const char *normal);
@@ -355,6 +357,14 @@ void parse_args(int argc, char* argv[])
 		exit(run_dhcp_discover());
 	}
 
+	// Password hashing performance test
+	if(argc > 1 && (strcmp(argv[1], "--perf") == 0 || strcmp(argv[1], "performance") == 0))
+	{
+		// Enable stdout printing
+		cli_mode = true;
+		exit(run_performance_test());
+	}
+
 	// ARP scanning mode
 	if(argc > 1 && strcmp(argv[1], "arp-scan") == 0)
 	{
@@ -817,6 +827,8 @@ void parse_args(int argc, char* argv[])
 			printf("\t                    interfaces and scan 10x more often\n");
 			printf("\t%s--totp%s              Generate valid TOTP token for 2FA\n", green, normal);
 			printf("\t                    authentication (if enabled)\n");
+			printf("\t%s--perf%s              Run performance-tests based on the\n", green, normal);
+			printf("\t                    BALLOON password-hashing algorithm\n");
 			printf("\t%s--%s [OPTIONS]%s        Pass OPTIONS to internal dnsmasq resolver\n", green, cyan, normal);
 			printf("\t%s-h%s, %shelp%s            Display this help and exit\n\n", green, normal, green, normal);
 			exit(EXIT_SUCCESS);
diff --git a/src/config/cli.c b/src/config/cli.c
index 5829b449..0b61548b 100644
--- a/src/config/cli.c
+++ b/src/config/cli.c
@@ -162,7 +162,7 @@ static bool readStringValue(struct conf_item *conf_item, const char *value, stru
 			char *pwhash = strlen(value) > 0 ? create_password(value) : strdup("");
 
 			// Verify that the password hash is valid
-			if(!verify_password(value, pwhash))
+			if(verify_password(value, pwhash, false) != PASSWORD_CORRECT)
 			{
 				log_err("Failed to create password hash (verification failed), password remains unchanged");
 				free(pwhash);
diff --git a/src/config/password.c b/src/config/password.c
index ebbe3caa..3fb676f3 100644
--- a/src/config/password.c
+++ b/src/config/password.c
@@ -14,6 +14,8 @@
 #include "password.h"
 // genrandom() with fallback
 #include "daemon.h"
+// sleepms()
+#include "timers.h"
 
 // Randomness generator
 #include "webserver/x509.h"
@@ -305,16 +307,39 @@ char * __attribute__((malloc)) create_password(const char *password)
 	return balloon_password(password, salt, true);
 }
 
-bool verify_password(const char *password, const char* pwhash)
+char verify_password(const char *password, const char* pwhash, const bool rate_limiting)
 {
 	// No password supplied
 	if(password == NULL || password[0] == '\0')
-		return false;
+		return PASSWORD_INCORRECT;
 
 	// No password set
 	if(pwhash == NULL || pwhash[0] == '\0')
-		return true;
+		return PASSWORD_CORRECT;
 
+	// Check if there has already been one login attempt within this second
+	static time_t last_password_attempt = 0;
+	static unsigned int num_password_attempts = 0;
+	if(rate_limiting &&
+	   last_password_attempt > 0 &&
+	   last_password_attempt == time(NULL))
+	{
+		// Check if we have reached the maximum number of attempts
+		if(++num_password_attempts > MAX_PASSWORD_ATTEMPTS_PER_SECOND)
+		{
+			// Rate limit reached
+			sleepms(250);
+			return PASSWORD_RATE_LIMITED;
+		}
+	}
+	else
+	{
+		// Reset counter
+		num_password_attempts = 1;
+		last_password_attempt = time(NULL);
+	}
+
+	// Check password hash format
 	if(pwhash[0] == '$')
 	{
 		// Parse PHC string
@@ -323,9 +348,9 @@ bool verify_password(const char *password, const char* pwhash)
 		uint8_t *salt = NULL;
 		uint8_t *config_hash = NULL;
 		if(!parse_PHC_string(pwhash, &s_cost, &t_cost, &salt, &config_hash))
-			return false;
+			return PASSWORD_INCORRECT;
 		if(salt == NULL || config_hash == NULL)
-			return false;
+			return PASSWORD_INCORRECT;
 		char *supplied = balloon_password(password, salt, false);
 		const bool result = memcmp(config_hash, supplied, SHA256_DIGEST_SIZE) == 0;
 
@@ -336,7 +361,7 @@ bool verify_password(const char *password, const char* pwhash)
 		if(config_hash != NULL)
 			free(config_hash);
 
-		return result;
+		return result ? PASSWORD_CORRECT : PASSWORD_INCORRECT;
 	}
 	else
 	{
@@ -361,6 +386,187 @@ bool verify_password(const char *password, const char* pwhash)
 			}
 		}
 
-		return result;
+		return result ? PASSWORD_CORRECT : PASSWORD_INCORRECT;
 	}
 }
+
+static double sqroot(double square)
+{
+	double root = square / 3.0;
+	if (square <= 0) return 0.0;
+	for (unsigned int i=0; i<32; i++)
+		root = (root + square / root) / 2;
+	return root;
+}
+
+static int performance_test_task(const size_t s_cost, const size_t t_cost, const uint8_t password[],
+                                 const size_t pwlen, uint8_t salt[SALT_LEN],
+                                 double *elapsed1, double *elapsed2)
+{
+		struct timespec start, end, end2;
+		// Scratch buffer scratch is a user allocated working space required by
+		// the algorithm.  To determine the required size of the scratch buffer
+		// use the utility function balloon_itch.  Output of BALLOON algorithm
+		// will be written into the output buffer dst that has to be at least
+		// digest_size bytes long.
+		const size_t scratch_size = balloon_itch(SHA256_DIGEST_SIZE, s_cost);
+		uint8_t *scratch = calloc(scratch_size, sizeof(uint8_t));
+		if(scratch == NULL)
+		{
+			printf("Could not allocate %zu bytes of memory for test!\n", scratch_size);
+			return -1;
+		}
+
+		// Record starting time
+		clock_gettime(CLOCK_MONOTONIC, &start);
+
+		// Compute hash of given password password salted with salt and write
+		// the result into the output buffer dst
+		balloon_sha256(s_cost, t_cost, pwlen, password, SALT_LEN, salt, scratch, scratch);
+
+		// Record end time
+		clock_gettime(CLOCK_MONOTONIC, &end);
+
+		// Compute hash of given password password salted with salt and write
+		// the result into the output buffer dst
+		balloon_sha256(s_cost, t_cost, pwlen, password, SALT_LEN, salt, scratch, scratch);
+
+		// Record end time
+		clock_gettime(CLOCK_MONOTONIC, &end2);
+
+		// Free allocated memory
+		free(scratch);
+
+		// Compute elapsed time
+		*elapsed1 = (end.tv_sec - start.tv_sec) + (end.tv_nsec - start.tv_nsec) / 1000000000.0;
+		*elapsed2 = (end2.tv_sec - end.tv_sec) + (end2.tv_nsec - end.tv_nsec) / 1000000000.0;
+		char prefix[2] = { 0 };
+		double formatted = 0.0;
+		format_memory_size(prefix, (unsigned long long)scratch_size, &formatted);
+		const double avg = (*elapsed1 + *elapsed2)/2;
+		const double stdev = sqroot(((*elapsed1 - avg)*(*elapsed1 - avg) + (*elapsed2 - avg)*(*elapsed2 - avg))/2);
+		printf("s = %5zu, t = %5zu took %6.1f +/- %4.1f ms (scratch buffer %6.1f%1sB) -> %.0f\n",
+		       s_cost, t_cost, 1e3*avg, 1e3*stdev, formatted, prefix, 1.0*(s_cost*t_cost)/avg);
+
+		// Break if test took longer than two seconds
+		if(avg > 2)
+			return 1;
+		return 0;
+}
+
+// Run performance tests until individual test result gets beyond 3 seconds
+int run_performance_test(void)
+{
+	struct timespec start, end;
+	// Record starting time
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	// Test password
+	const uint8_t password[] = "abcdefghijklmnopqrstuvwxyz0123456789!\"§$%&/()=?";
+
+	// Generate a 128 bit random salt
+	// genrandom() returns cryptographically secure random data
+	uint8_t salt[SALT_LEN] = { 0 };
+	if(getrandom(salt, sizeof(salt), 0) < 0)
+	{
+		printf("Could not generate random salt!\n");
+		return EXIT_FAILURE;
+	}
+
+	printf("Running time-performance test:\n");
+	size_t t_t_cost = 16;
+	const size_t t_s_cost = 512;
+	cJSON *time_test = cJSON_CreateArray();
+	unsigned int i = 0;
+	while(true)
+	{
+		double elapsed1 = 0.0, elapsed2 = 0.0;
+		const int ret = performance_test_task(t_s_cost, t_t_cost, password, sizeof(password), salt,
+		                                      &elapsed1, &elapsed2);
+
+		if(ret == -1)
+			return EXIT_FAILURE;
+
+		if(i > 0)
+		{
+			// We do not want to include the first test in the
+			// average as the first call is slower
+			cJSON_AddItemToArray(time_test, cJSON_CreateNumber(1.0*(t_s_cost*t_t_cost)/elapsed1));
+			cJSON_AddItemToArray(time_test, cJSON_CreateNumber(1.0*(t_s_cost*t_t_cost)/elapsed2));
+		}
+
+		if(ret == 1)
+			break;
+
+		// Double time costs
+		t_t_cost *= 2;
+		i++;
+	}
+
+	printf("\nRunning space-performance test:\n");
+	const size_t s_t_cost = 512;
+	size_t s_s_cost = 8;
+	cJSON *space_test = cJSON_CreateArray();
+	while(true)
+	{
+		double elapsed1 = 0.0, elapsed2 = 0.0;
+		const int ret = performance_test_task(s_s_cost, s_t_cost, password, sizeof(password), salt,
+		                                      &elapsed1, &elapsed2);
+
+		cJSON_AddItemToArray(space_test, cJSON_CreateNumber(1.0*(s_t_cost*s_s_cost)/elapsed1));
+		cJSON_AddItemToArray(space_test, cJSON_CreateNumber(1.0*(s_t_cost*s_s_cost)/elapsed2));
+
+		if(ret == -1)
+			return EXIT_FAILURE;
+		else if(ret == 1)
+			break;
+
+		// Double space costs
+		s_s_cost *= 2;
+	}
+
+	clock_gettime(CLOCK_MONOTONIC, &end);
+	const double elapsed = (end.tv_sec - start.tv_sec) + (end.tv_nsec - start.tv_nsec) / 1000000000.0;
+
+	// Compute average time and space costs from data in cJSON arrays
+	cJSON *item = NULL;
+	double t_avg_sum1 = 0.0;
+	cJSON_ArrayForEach(item, time_test)
+	{
+		t_avg_sum1 += item->valuedouble;
+	}
+	t_avg_sum1 /= cJSON_GetArraySize(time_test);
+
+	double s_avg_sum1 = 0.0;
+	cJSON_ArrayForEach(item, space_test)
+	{
+		s_avg_sum1 += item->valuedouble;
+	}
+	s_avg_sum1 /= cJSON_GetArraySize(space_test);
+
+	// Get standard deviations
+	double t_stdev_sum1 = 0.0;
+	cJSON_ArrayForEach(item, time_test)
+	{
+		t_stdev_sum1 += (item->valuedouble - t_avg_sum1)*(item->valuedouble - t_avg_sum1);
+	}
+	t_stdev_sum1 = sqroot(t_stdev_sum1/cJSON_GetArraySize(time_test));
+
+	double s_stdev_sum1 = 0.0;
+	cJSON_ArrayForEach(item, space_test)
+	{
+		s_stdev_sum1 += (item->valuedouble - s_avg_sum1)*(item->valuedouble - s_avg_sum1);
+	}
+	s_stdev_sum1 = sqroot(s_stdev_sum1/cJSON_GetArraySize(space_test));
+
+	// Free allocated memory
+	cJSON_Delete(time_test);
+	cJSON_Delete(space_test);
+
+	// Print results
+	printf("\nAverage time-performance index:  %9.0f +/- %.0f (s = %zu)\n", t_avg_sum1, t_stdev_sum1, t_s_cost);
+	printf("Average space-performance index: %9.0f +/- %.0f (t = %zu)\n", s_avg_sum1, s_stdev_sum1, s_t_cost);
+	printf("\nTotal test time: %.1f seconds\n\n", elapsed);
+
+	return EXIT_SUCCESS;
+}
diff --git a/src/config/password.h b/src/config/password.h
index 6cacc758..e0a3a5f2 100644
--- a/src/config/password.h
+++ b/src/config/password.h
@@ -16,6 +16,16 @@
 
 void sha256_raw_to_hex(uint8_t *data, char *buffer);
 char *create_password(const char *password) __attribute__((malloc));
-bool verify_password(const char *password, const char *pwhash);
+char verify_password(const char *password, const char *pwhash, const bool rate_limiting);
+int run_performance_test(void);
+
+enum password_result {
+	PASSWORD_INCORRECT = 0,
+	PASSWORD_CORRECT = 1,
+	PASSWORD_RATE_LIMITED = -1
+} __attribute__((packed));
+
+// The maximum number of password attempts per second
+#define MAX_PASSWORD_ATTEMPTS_PER_SECOND 3
 
 #endif //PASSWORD_H
diff --git a/test/api/libs/FTLAPI.py b/test/api/libs/FTLAPI.py
index 2b2519dc..a71bcec2 100644
--- a/test/api/libs/FTLAPI.py
+++ b/test/api/libs/FTLAPI.py
@@ -43,9 +43,10 @@ class FTLAPI():
 		self.verbose = False
 
 		# Login to FTL API
-		self.login(password)
-		if self.session is None or 'valid' not in self.session or not self.session['valid']:
-			raise Exception("Could not login to FTL API")
+		if password is not None:
+			self.login(password)
+			if self.session is None or 'valid' not in self.session or not self.session['valid']:
+				raise Exception("Could not login to FTL API")
 
 	def login(self, password: str = None):
 		# Check if we even need to login
@@ -65,6 +66,8 @@ class FTLAPI():
 			return
 
 		response = self.POST("/api/auth", {"password": password})
+		if "error" in response:
+			raise Exception("FTL returned error: " + json.dumps(response["error"]))
 		if 'session' not in response:
 			raise Exception("FTL returned invalid response item")
 		self.session = response["session"]
diff --git a/test/api/test-rate-limit.py b/test/api/test-rate-limit.py
new file mode 100644
index 00000000..781a2d73
--- /dev/null
+++ b/test/api/test-rate-limit.py
@@ -0,0 +1,24 @@
+# Script that sends a number of randomly generated passwords to the
+# /api/auth endpoint checking that rate limiting is enforced
+import random
+import string
+from libs.FTLAPI import FTLAPI
+
+if __name__ == "__main__":
+	# Create FTLAPI object
+	ftl = FTLAPI("http://127.0.0.1:8080")
+
+	# Try to login with random passwords
+	for i in range(0, 100):
+		pw = "".join(random.choices(string.printable, k=random.randint(1, 64)))
+		try:
+			ftl.login(pw)
+		except Exception as e:
+			if "too_many_requests" in str(e):
+				print("Rate-limited on attempt no. "  + str(i))
+				exit(0)
+			else:
+				print("Unexpected error: " + str(e))
+				exit(1)
+	print("Rate-limiting was not enforced")
+	exit(1)
diff --git a/test/run.sh b/test/run.sh
index 6f6454ed..e2563e82 100755
--- a/test/run.sh
+++ b/test/run.sh
@@ -130,6 +130,11 @@ kill "$(pidof pihole-FTL)"
 # Restore umask
 umask "$OLDUMASK"
 
+# Run performance tests
+if ! su pihole -s /bin/sh -c "/home/pihole/pihole-FTL --perf"; then
+  echo "pihole-FTL --perf failed to start"
+fi
+
 # Remove copied file
 rm /home/pihole/pihole-FTL