Letterfork vs PostNext

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.

PostNext is a social media planning and publishing tool for composing drafts and scheduling posts across X, Instagram, LinkedIn, TikTok, YouTube, Threads and Bluesky. Its visual calendar supports advance planning, moving posts between dates and best-time suggestions. Users can prepare videos, photos, text updates, image carousels and reels for scheduled or instant posting. AI tools generate captions, hashtags, ideas and images, and offer fact-checking; text and prompts are sent to OpenAI and Google Gemini for processing. Team workspaces support role-based access, draft review and shared content libraries, while brand profiles separate each brand's voice, assets and channel logins. Access is listed for web, Android, iOS, API and extension, including a Chrome extension for sharing pages, images or selected text into drafts. The free plan costs nothing and allows one connected account, one user and 10 scheduled posts per month. Premium costs $11 a month, billed €11 / month; Business costs $39 a month, billed €39 / month. Teams costs $4 a month, billed €4 / user / month, from €20 / month, with a five-seat minimum.