Castmagic vs Letterfork

Castmagic converts long-form audio and video into transcripts and drafts such as show notes, summaries, blogs, social posts, and newsletters. Transcription supports more than 60 languages, with speaker labels, timestamps, translation, and SRT, VTT, PDF, and DOCX exports. Recurring prompts, brand voice settings, and custom prompts can generate a content set when recordings arrive. Studio creates image carousels, captioned clips in 9:16, 1:1, or 16:9 formats, and audiograms. Its content strategist answers questions across recordings, cites source moments, and drafts weekly content plans. The library connects with Zoom, Loom, Google Drive, RSS, and Zapier, and imports from YouTube, Spotify, Apple Podcasts, TikTok, Instagram, Vimeo, Twitch, Reddit, and Wistia. A REST API imports recordings and retrieves transcripts and generated content; a Claude connector can access a library. The iOS app records into a space or captures voice memos. Castmagic runs on web, iOS, and API. Plans start at $19/mo (annual), with no free plan. Listed hour allowances are 30 for Hobby, 100 for Starter, and 400 for Team.

Letterfork turns newsletter content into plain-text social posts shaped around the writer’s voice. It produces posts for LinkedIn, X, Bluesky, Substack Notes, Threads, Instagram, and Reddit. To build a voice profile, it uses 5–10 past newsletters to identify patterns in sentence rhythm, openings, vocabulary, and humor. Users can provide a newsletter URL or paste the full text. URL parsing works only for publicly visible pages; the maker says Substack, Beehiiv, and Ghost work, while newsletters from other sources can be pasted. Outputs are for copying and pasting, not automatic publishing. The free plan costs nothing and includes 3 rewrites total across all seven platforms. Starter is $9 a month for 10 rewrites per month and one Voice Profile; Pro is $19 a month with unlimited rewrites and three Voice Profiles; Unlimited is $39 a month and adds unlimited Voice Profiles and API access marked as coming soon. Paid tiers renew monthly or yearly until cancelled, with self-service cancellation through the Stripe Customer Portal. The maker says it does not train AI models on submitted content or sell user data.