diff --git a/app/soapbox/schemas/attachment.ts b/app/soapbox/schemas/attachment.ts
new file mode 100644
index 000000000..44b9cb126
--- /dev/null
+++ b/app/soapbox/schemas/attachment.ts
@@ -0,0 +1,89 @@
+import { isBlurhashValid } from 'blurhash';
+import { z } from 'zod';
+
+const blurhashSchema = z.string().superRefine((value, ctx) => {
+  const r = isBlurhashValid(value);
+
+  if (!r.result) {
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      message: r.errorReason,
+    });
+  }
+});
+
+const baseAttachmentSchema = z.object({
+  blurhash: blurhashSchema.nullable().catch(null),
+  description: z.string().catch(''),
+  external_video_id: z.string().optional().catch(undefined), // TruthSocial
+  id: z.string(),
+  pleroma: z.object({
+    mime_type: z.string().regex(/^\w+\/[-+.\w]+$/),
+  }).optional().catch(undefined),
+  preview_url: z.string().url().catch(''),
+  remote_url: z.string().url().nullable().catch(null),
+  type: z.string(),
+  url: z.string().url(),
+});
+
+const imageMetaSchema = z.object({
+  width: z.number(),
+  height: z.number(),
+  aspect: z.number().optional().catch(undefined),
+}).transform((meta) => ({
+  ...meta,
+  aspect: typeof meta.aspect === 'number' ? meta.aspect : meta.width / meta.height,
+}));
+
+const imageAttachmentSchema = baseAttachmentSchema.extend({
+  type: z.literal('image'),
+  meta: z.object({
+    original: imageMetaSchema.optional().catch(undefined),
+  }).catch({}),
+});
+
+const videoAttachmentSchema = baseAttachmentSchema.extend({
+  type: z.literal('video'),
+  meta: z.object({
+    duration: z.number().optional().catch(undefined),
+    original: imageMetaSchema.optional().catch(undefined),
+  }).catch({}),
+});
+
+const gifvAttachmentSchema = baseAttachmentSchema.extend({
+  type: z.literal('gifv'),
+  meta: z.object({
+    duration: z.number().optional().catch(undefined),
+    original: imageMetaSchema.optional().catch(undefined),
+  }).catch({}),
+});
+
+const audioAttachmentSchema = baseAttachmentSchema.extend({
+  type: z.literal('audio'),
+  meta: z.object({
+    duration: z.number().optional().catch(undefined),
+  }).catch({}),
+});
+
+const unknownAttachmentSchema = baseAttachmentSchema.extend({
+  type: z.literal('unknown'),
+});
+
+/** https://docs.joinmastodon.org/entities/attachment */
+const attachmentSchema = z.discriminatedUnion('type', [
+  imageAttachmentSchema,
+  videoAttachmentSchema,
+  gifvAttachmentSchema,
+  audioAttachmentSchema,
+  unknownAttachmentSchema,
+]).transform((attachment) => {
+  if (!attachment.preview_url) {
+    attachment.preview_url = attachment.url;
+  }
+
+  return attachment;
+});
+
+type Attachment = z.infer<typeof attachmentSchema>;
+
+export { attachmentSchema, type Attachment };
\ No newline at end of file