diff --git a/packages/backend/migration/1669545702493-detectDeeplPro.js b/packages/backend/migration/1669545702493-detectDeeplPro.js
new file mode 100644
index 000000000..2a75ff228
--- /dev/null
+++ b/packages/backend/migration/1669545702493-detectDeeplPro.js
@@ -0,0 +1,12 @@
+export class detectDeeplPro1669545702493 {
+	name = 'detectDeeplPro1669545702493';
+
+	async up(queryRunner) {
+		await queryRunner.query(`ALTER TABLE "meta" DROP COLUMN "deeplIsPro"`);
+	}
+
+	async down(queryRunner) {
+		await queryRunner.query(`ALTER TABLE "meta" ADD "deeplIsPro" boolean NOT NULL DEFAULT false`);
+		await queryRunner.query(`UPDATE "meta" SET "deeplIsPro" = true WHERE "deeplAuthKey" IS NOT NULL AND "deeplAuthKey" NOT LIKE '%:fx'`);
+	}
+}
diff --git a/packages/backend/src/models/entities/meta.ts b/packages/backend/src/models/entities/meta.ts
index 565d95a32..59118303e 100644
--- a/packages/backend/src/models/entities/meta.ts
+++ b/packages/backend/src/models/entities/meta.ts
@@ -316,11 +316,6 @@ export class Meta {
 	})
 	public deeplAuthKey: string | null;
 
-	@Column('boolean', {
-		default: false,
-	})
-	public deeplIsPro: boolean;
-
 	@Column('varchar', {
 		length: 128,
 		nullable: true,
diff --git a/packages/backend/src/server/api/endpoints/admin/meta.ts b/packages/backend/src/server/api/endpoints/admin/meta.ts
index f4ee7c480..32e05dacb 100644
--- a/packages/backend/src/server/api/endpoints/admin/meta.ts
+++ b/packages/backend/src/server/api/endpoints/admin/meta.ts
@@ -280,10 +280,6 @@ export const meta = {
 				type: 'string',
 				optional: true, nullable: true,
 			},
-			deeplIsPro: {
-				type: 'boolean',
-				optional: true, nullable: false,
-			},
 			libreTranslateEndpoint: {
 				type: 'string',
 				optional: true, nullable: true,
@@ -382,7 +378,6 @@ export default define(meta, paramDef, async (ps, me) => {
 		translatorAvailable: translatorAvailable(instance),
 		translationService: instance.translationService,
 		deeplAuthKey: instance.deeplAuthKey,
-		deeplIsPro: instance.deeplIsPro,
 		libreTranslateEndpoint: instance.libreTranslateEndpoint,
 		libreTranslateAuthKey: instance.libreTranslateAuthKey,
 	};
diff --git a/packages/backend/src/server/api/endpoints/admin/update-meta.ts b/packages/backend/src/server/api/endpoints/admin/update-meta.ts
index 5958b3c98..e6bcc4012 100644
--- a/packages/backend/src/server/api/endpoints/admin/update-meta.ts
+++ b/packages/backend/src/server/api/endpoints/admin/update-meta.ts
@@ -58,7 +58,6 @@ export const paramDef = {
 		summalyProxy: { type: 'string', nullable: true },
 		translationService: { type: 'string', nullable: true, enum: [null, ...Object.values(TranslationService)] },
 		deeplAuthKey: { type: 'string', nullable: true },
-		deeplIsPro: { type: 'boolean' },
 		libreTranslateAuthKey: { type: 'string', nullable: true },
 		libreTranslateEndpoint: { type: 'string', nullable: true },
 		enableTwitterIntegration: { type: 'boolean' },
@@ -378,10 +377,6 @@ export default define(meta, paramDef, async (ps, me) => {
 		}
 	}
 
-	if (ps.deeplIsPro !== undefined) {
-		set.deeplIsPro = ps.deeplIsPro;
-	}
-
 	if (ps.libreTranslateEndpoint !== undefined) {
 		if (ps.libreTranslateEndpoint === '') {
 			set.libreTranslateEndpoint = null;
diff --git a/packages/backend/src/server/api/endpoints/notes/translate.ts b/packages/backend/src/server/api/endpoints/notes/translate.ts
index 44057415a..93ad1a182 100644
--- a/packages/backend/src/server/api/endpoints/notes/translate.ts
+++ b/packages/backend/src/server/api/endpoints/notes/translate.ts
@@ -139,7 +139,11 @@ export default define(meta, paramDef, async (ps, user) => {
 		params.append('target_lang', targetLang);
 		if (sourceLang) params.append('source_lang', sourceLang);
 
-		const endpoint = instance.deeplIsPro ? 'https://api.deepl.com/v2/translate' : 'https://api-free.deepl.com/v2/translate';
+		// From the DeepL API docs:
+		//> DeepL API Free authentication keys can be identified easily by the suffix ":fx"
+		const endpoint = instance.deeplAuthKey.endsWith(':fx')
+			? 'https://api-free.deepl.com/v2/translate'
+			: 'https://api.deepl.com/v2/translate';
 
 		const res = await fetch(endpoint, {
 			method: 'POST',
diff --git a/packages/client/src/pages/admin/translation-settings.vue b/packages/client/src/pages/admin/translation-settings.vue
index 15085940b..a67b98969 100644
--- a/packages/client/src/pages/admin/translation-settings.vue
+++ b/packages/client/src/pages/admin/translation-settings.vue
@@ -12,9 +12,6 @@
 				</FormSelect>
 
 				<template v-if="translationService === 'deepl'">
-					<FormSwitch v-model="deeplIsPro" class="_formBlock">
-						<template #label>{{ i18n.ts._translationService._deepl.pro }}</template>
-					</FormSwitch>
 					<FormInput v-model="deeplAuthKey" class="_formBlock">
 						<template #prefix><i class="fas fa-key"></i></template>
 						<template #label>{{ i18n.ts._translationService._deepl.authKey }}</template>
@@ -46,7 +43,6 @@ import { fetchInstance } from '@/instance';
 import { definePageMetadata } from '@/scripts/page-metadata';
 
 let translationService: string = $ref('none');
-let deeplIsPro: boolean = $ref(false);
 let deeplAuthKey: string = $ref('');
 let libreTranslateEndpoint: string = $ref('');
 let libreTranslateAuthKey: string = $ref('');
@@ -54,7 +50,6 @@ let libreTranslateAuthKey: string = $ref('');
 async function init(): Promise<void> {
 	const meta = await os.api('admin/meta');
 	translationService = meta.translationService ?? 'none';
-	deeplIsPro = meta.deeplIsPro;
 	deeplAuthKey = meta.deeplAuthKey;
 	libreTranslateEndpoint = meta.libreTranslateEndpoint;
 	libreTranslateAuthKey = meta.libreTranslateAuthKey;
@@ -64,7 +59,6 @@ function save(): void {
 	os.apiWithDialog('admin/update-meta', {
 		translationService: translationService === 'none' ? null : translationService,
 		deeplAuthKey,
-		deeplIsPro,
 		libreTranslateEndpoint,
 		libreTranslateAuthKey,
 	}).then(() => {