CastPost — Podcast-to-LinkedIn Content Pipeline
Upload a podcast episode (MP3/YouTube URL) -> AI extracts key insights -> generates 20-30 LinkedIn posts in varied formats -> schedule with timestamped backlinks to the episode.
// how this PRD was built
Generated using Solo Factory + Solograph -- two open-source tools that turn Claude Code into a startup factory with memory and skills.
/solo:research → /solo:validate → PRD with score, stack, risks, launch strategy
npx skills add fortunto2/solo-factory --all claude mcp add -s project solograph -- uvx solograph
Problem
B2B solopreneurs record podcast episodes packed with insights but struggle to distribute them. LinkedIn is the #1 B2B channel — 1B members, 65M decision-makers — but turning a 45-minute episode into 20+ posts takes 4-8 hours manually.
Existing tools (Swell AI, Castmagic, Capsho) generate generic social posts as an afterthought — none are LinkedIn-first. None generate 20-30 posts per episode. None link back to specific timestamps. None include native scheduling.
The gap: No tool does the full loop: podcast -> AI extraction -> LinkedIn-native multi-format content -> scheduling with timestamp backlinks -> analytics.
Why Now
- LinkedIn 25% YoY engagement growth. Native scheduling API now available to third-party apps
- Justin Welsh built $8M/yr primarily through LinkedIn — proving the channel works for solopreneurs
- Cody Schneider described needing 4+ tools stitched together for the full podcast-to-social pipeline
- AI transcription cost dropped 95%. Deepgram: $0.0043/min. Generating 30 posts costs <$0.15
- 500M+ podcast listeners globally. 67% of business podcasters also have LinkedIn presence
ICP
Primary: B2B solopreneurs and consultants (30-55) who host or appear on podcasts regularly and have 1K-50K LinkedIn followers. Coaches, agency owners, SaaS founders, newsletter writers.
Secondary: Podcast production agencies managing 5-20 client shows.
| JTBD | Current Solution | Pain |
|---|---|---|
| Turn 1hr episode into a month of content | Manual: listen, note, write (4-8 hours) | Critical |
| Drive listeners with deep links | No tool does timestamp backlinks | Unmet |
| Post consistently without writing hours | Batch tools produce 3-5 generic posts | High |
| Sound like me, not like AI | Generic AI copy, no voice learning | High |
MVP Features
F1: Episode Upload + AI Extraction
Upload MP3/MP4 or paste YouTube URL. AI transcribes, identifies speakers, extracts 15-30 key insights with timestamps.
- Transcription in <3 minutes for 60min episode
- Speaker diarization (2-4 speakers)
- Each insight: verbatim quote, summary, topic tag, timestamp
F2: LinkedIn Post Generator (Multi-Format)
Generate 20-30 posts in 7 proven formats:
- Storytelling — “3 years ago I believed X. Then I learned Y…”
- Listicle — “5 things I learned from recording 200 episodes”
- Hot take — “Unpopular opinion: [contrarian insight]”
- Thread/carousel — multi-slide breakdown
- Quote card — best verbatim quote with attribution
- Lesson learned — “The biggest mistake I see in [topic]…”
- Question hook — “What would you do if [scenario]?”
Each post includes timestamp link: “Full conversation at 23:15”
F3: Content Calendar + LinkedIn Scheduling
Drag-and-drop calendar. LinkedIn OAuth for direct posting. Optimal posting time suggestions. Auto-distribute 20+ posts across 2-4 weeks.
F4: Brand Voice Learning
Import last 50 LinkedIn posts. Detect writing patterns. Generate “voice profile.” Apply to all post generation.
Competitor Analysis
| Competitor | Price | LinkedIn Posts/ep | Timestamp Links | Scheduling |
|---|---|---|---|---|
| CastPost | $19-99/mo | 20-30 | Yes | Native |
| Castmagic | $29-299/mo | 3-5 | No | No |
| Swell AI | $29-99/mo | 3-5 | No | No |
| Capsho | $29-99/mo | 5-10 | No | No |
| Taplio | $39-149/mo | AI writing only | N/A | Yes |
Moat: The only tool combining podcast-specific extraction with LinkedIn-native multi-format generation and timestamped deep links.
Pricing
| Tier | Price | Limits |
|---|---|---|
| Free | $0/mo | 1 episode/mo, 5 posts, copy-paste |
| Creator | $19/mo | 4 episodes, 80 posts, scheduling, voice |
| Pro | $49/mo | Unlimited, analytics, carousel export |
| Agency | $99/mo | 5 profiles, team seats, API |
Unit economics: AI cost ~$0.37/episode. Creator at $19/mo for 4 episodes = $4.75/episode revenue. Gross margin 92%.
Tech Stack
Frontend: Next.js 16 + React 19 + Tailwind 4 + shadcn-ui + @dnd-kit
Backend: Supabase (PostgreSQL + Auth + Realtime + Storage)
AI: Deepgram Nova-3 (transcription) + Claude Sonnet (extraction/generation)
Integration: LinkedIn Marketing API (OAuth + posting + analytics)
Payments: Stripe
Hosting: VercelValidation Summary (STREAM)
| Layer | Score | Key Factor |
|---|---|---|
| Scope | 7/10 | Strong tech, LinkedIn creator domain outside circle |
| Time | 7/10 | Good window, but AI content fatigue risk |
| Route | 8/10 | Clear MVP path, 3-5 days to ship |
| Exposure | 8/10 | $200 downside, $37K upside. Excellent asymmetry |
| Audience | 6/10 | No network effects, low switching costs |
| Meta | 6/10 | Valid experiment, must stay time-boxed |
Overall: 7.0/10 — Best candidate for immediate action.
No S.E.E.D. kill flags triggered. Rankable niche, strong evidence, feasible MVP, proven monetization.
Recommendation: Fake-Door landing page (1 day), $20 Reddit/LinkedIn ads. If >20 CTA clicks, build MVP in 3-5 days.
Launch Strategy
- Day 0: Landing page at castpost.io
- Day 1-3: Post on LinkedIn (dogfood the concept), r/podcasting, r/content_marketing
- If validated: Build MVP (upload -> generate -> copy-paste) in 3-5 days
- Week 2-3: 10-20 beta users, iterate on post quality
- Week 4: Add scheduling (Phase 2) only after retention signal