diff --git a/packages/backend/src/server/api/SigninApiService.ts b/packages/backend/src/server/api/SigninApiService.ts
index 2d9195bf02ec..58becdbc3235 100644
--- a/packages/backend/src/server/api/SigninApiService.ts
+++ b/packages/backend/src/server/api/SigninApiService.ts
@@ -20,6 +20,9 @@ import { bindThis } from '@/decorators.js';
 import { WebAuthnService } from '@/core/WebAuthnService.js';
 import { UserAuthService } from '@/core/UserAuthService.js';
 import { LoggerService } from '@/core/LoggerService.js';
+import { CaptchaService } from '@/core/CaptchaService.js';
+import { FastifyReplyError } from '@/misc/fastify-reply-error.js';
+import { MetaService } from '@/core/MetaService.js';
 import { RateLimiterService } from './RateLimiterService.js';
 import { SigninService } from './SigninService.js';
 import type { AuthenticationResponseJSON } from '@simplewebauthn/types';
@@ -46,6 +49,8 @@ export class SigninApiService {
 		private signinService: SigninService,
 		private userAuthService: UserAuthService,
 		private webAuthnService: WebAuthnService,
+		private metaService: MetaService,
+		private captchaService: CaptchaService,
 	) {
 	}
 
@@ -57,6 +62,10 @@ export class SigninApiService {
 				password: string;
 				token?: string;
 				credential?: AuthenticationResponseJSON;
+				'hcaptcha-response'?: string;
+				'g-recaptcha-response'?: string;
+				'turnstile-response'?: string;
+				'm-captcha-response'?: string;
 			};
 		}>,
 		reply: FastifyReply,
@@ -157,6 +166,33 @@ export class SigninApiService {
 		};
 
 		if (!profile.twoFactorEnabled) {
+			if (process.env.NODE_ENV !== 'test') {
+				const meta = await this.metaService.fetch();
+				if (meta.enableHcaptcha && meta.hcaptchaSecretKey) {
+					await this.captchaService.verifyHcaptcha(meta.hcaptchaSecretKey, body['hcaptcha-response']).catch(err => {
+						throw new FastifyReplyError(400, err);
+					});
+				}
+
+				if (meta.enableMcaptcha && meta.mcaptchaSecretKey && meta.mcaptchaSitekey && meta.mcaptchaInstanceUrl) {
+					await this.captchaService.verifyMcaptcha(meta.mcaptchaSecretKey, meta.mcaptchaSitekey, meta.mcaptchaInstanceUrl, body['m-captcha-response']).catch(err => {
+						throw new FastifyReplyError(400, err);
+					});
+				}
+
+				if (meta.enableRecaptcha && meta.recaptchaSecretKey) {
+					await this.captchaService.verifyRecaptcha(meta.recaptchaSecretKey, body['g-recaptcha-response']).catch(err => {
+						throw new FastifyReplyError(400, err);
+					});
+				}
+
+				if (meta.enableTurnstile && meta.turnstileSecretKey) {
+					await this.captchaService.verifyTurnstile(meta.turnstileSecretKey, body['turnstile-response']).catch(err => {
+						throw new FastifyReplyError(400, err);
+					});
+				}
+			}
+
 			if (same) {
 				logger.info('Successfully signed in with password.');
 				return this.signinService.signin(request, reply, user);
diff --git a/packages/frontend/src/components/MkCaptcha.vue b/packages/frontend/src/components/MkCaptcha.vue
index c64bb47e771b..dba01235c09c 100644
--- a/packages/frontend/src/components/MkCaptcha.vue
+++ b/packages/frontend/src/components/MkCaptcha.vue
@@ -91,6 +91,7 @@ if (loaded || props.provider === 'mcaptcha') {
 
 function reset() {
 	if (captcha.value.reset) captcha.value.reset();
+	emit('update:modelValue', null);
 }
 
 async function requestRender() {
diff --git a/packages/frontend/src/components/MkSignin.vue b/packages/frontend/src/components/MkSignin.vue
index 4b8f6d45ca08..3cae3ff59232 100644
--- a/packages/frontend/src/components/MkSignin.vue
+++ b/packages/frontend/src/components/MkSignin.vue
@@ -19,7 +19,11 @@ SPDX-License-Identifier: AGPL-3.0-only
 				<template #prefix><i class="ti ti-lock"></i></template>
 				<template #caption><button class="_textButton" type="button" @click="resetPassword">{{ i18n.ts.forgotPassword }}</button></template>
 			</MkInput>
-			<MkButton type="submit" large primary rounded :disabled="!user || signing" style="margin: 0 auto;">{{ signing ? i18n.ts.loggingIn : i18n.ts.login }}</MkButton>
+			<MkCaptcha v-if="!user?.twoFactorEnabled && instance.enableHcaptcha" ref="hcaptcha" v-model="hCaptchaResponse" :class="$style.captcha" provider="hcaptcha" :sitekey="instance.hcaptchaSiteKey"/>
+			<MkCaptcha v-if="!user?.twoFactorEnabled && instance.enableMcaptcha" ref="mcaptcha" v-model="mCaptchaResponse" :class="$style.captcha" provider="mcaptcha" :sitekey="instance.mcaptchaSiteKey" :instanceUrl="instance.mcaptchaInstanceUrl"/>
+			<MkCaptcha v-if="!user?.twoFactorEnabled && instance.enableRecaptcha" ref="recaptcha" v-model="reCaptchaResponse" :class="$style.captcha" provider="recaptcha" :sitekey="instance.recaptchaSiteKey"/>
+			<MkCaptcha v-if="!user?.twoFactorEnabled && instance.enableTurnstile" ref="turnstile" v-model="turnstileResponse" :class="$style.captcha" provider="turnstile" :sitekey="instance.turnstileSiteKey"/>
+			<MkButton type="submit" large primary rounded :disabled="!user || captchaFailed || signing" style="margin: 0 auto;">{{ signing ? i18n.ts.loggingIn : i18n.ts.login }}</MkButton>
 		</div>
 		<div v-if="totpLogin" class="2fa-signin" :class="{ securityKeys: user && user.securityKeys }">
 			<div v-if="user && user.securityKeys" class="twofa-group tap-group">
@@ -49,7 +53,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 </template>
 
 <script lang="ts" setup>
-import { defineAsyncComponent, ref } from 'vue';
+import { computed, defineAsyncComponent, ref } from 'vue';
 import { toUnicode } from 'punycode/';
 import * as Misskey from 'misskey-js';
 import { supported as webAuthnSupported, get as webAuthnRequest, parseRequestOptionsFromJSON } from '@github/webauthn-json/browser-ponyfill';
@@ -62,6 +66,8 @@ import * as os from '@/os.js';
 import { misskeyApi } from '@/scripts/misskey-api.js';
 import { login } from '@/account.js';
 import { i18n } from '@/i18n.js';
+import { instance } from '@/instance.js';
+import MkCaptcha, { type Captcha } from '@/components/MkCaptcha.vue';
 
 const signing = ref(false);
 const userAbortController = ref<AbortController>();
@@ -74,6 +80,22 @@ const totpLogin = ref(false);
 const isBackupCode = ref(false);
 const queryingKey = ref(false);
 const credentialRequest = ref<CredentialRequestOptions | null>(null);
+const hcaptcha = ref<Captcha | undefined>();
+const mcaptcha = ref<Captcha | undefined>();
+const recaptcha = ref<Captcha | undefined>();
+const turnstile = ref<Captcha | undefined>();
+const hCaptchaResponse = ref<string | null>(null);
+const mCaptchaResponse = ref<string | null>(null);
+const reCaptchaResponse = ref<string | null>(null);
+const turnstileResponse = ref<string | null>(null);
+
+const captchaFailed = computed((): boolean => {
+	return !user.value?.twoFactorEnabled && (
+		instance.enableHcaptcha && !hCaptchaResponse.value ||
+		instance.enableMcaptcha && !mCaptchaResponse.value ||
+		instance.enableRecaptcha && !reCaptchaResponse.value ||
+		instance.enableTurnstile && !turnstileResponse.value);
+});
 
 const emit = defineEmits<{
 	(ev: 'login', v: any): void;
@@ -170,6 +192,10 @@ function onSubmit(): void {
 		misskeyApi('signin', {
 			username: username.value,
 			password: password.value,
+			'hcaptcha-response': hCaptchaResponse.value,
+			'm-captcha-response': mCaptchaResponse.value,
+			'g-recaptcha-response': reCaptchaResponse.value,
+			'turnstile-response': turnstileResponse.value,
 			token: user.value?.twoFactorEnabled ? token.value : undefined,
 		}).then(res => {
 			emit('login', res);
@@ -179,6 +205,11 @@ function onSubmit(): void {
 }
 
 function loginFailed(err: any): void {
+	hcaptcha.value?.reset?.();
+	mcaptcha.value?.reset?.();
+	recaptcha.value?.reset?.();
+	turnstile.value?.reset?.();
+
 	switch (err.id) {
 		case '6cc579cc-885d-43d8-95c2-b8c7fc963280': {
 			os.alert({
diff --git a/packages/frontend/src/components/MkSignupDialog.form.vue b/packages/frontend/src/components/MkSignupDialog.form.vue
index 4c923de37543..e9859d4b1c13 100644
--- a/packages/frontend/src/components/MkSignupDialog.form.vue
+++ b/packages/frontend/src/components/MkSignupDialog.form.vue
@@ -90,6 +90,7 @@ const emit = defineEmits<{
 const host = toUnicode(config.host);
 
 const hcaptcha = ref<Captcha | undefined>();
+const mcaptcha = ref<Captcha | undefined>();
 const recaptcha = ref<Captcha | undefined>();
 const turnstile = ref<Captcha | undefined>();
 
@@ -217,6 +218,7 @@ async function onSubmit(): Promise<void> {
 	} catch {
 		submitting.value = false;
 		hcaptcha.value?.reset?.();
+		mcaptcha.value?.reset?.();
 		recaptcha.value?.reset?.();
 		turnstile.value?.reset?.();
 	}