Generate, publish and sell production-grade audio — voices, music, SFX, ambient — paid for in credits. Powered by ElevenLabs and Stripe.
Built for the Stripe + ElevenLabs Hackathon 2026 (ElevenHacks). Test mode only — no real charges.
Stock audio sites are slow, expensive, and royalty-encumbered. Voice cloning APIs are gated behind enterprise pricing. Creators have no easy way to monetise the voices and sound libraries they generate.
Multiverse fuses both halves into one marketplace. Buyers discover audio, pay in credits, and use it. Creators design voices, generate packs, and earn royalties. One credit economy. One Stripe-backed checkout. One ElevenLabs pipeline behind every sound.
- What is Multiverse?
- How It Works
- Key Features
- Audio Pipelines
- Stripe Integration
- ElevenLabs Integration
- Pricing
- Tech Stack
- Screenshots
- Running Locally
- Deploy
- Coming Soon
- License
Multiverse has four product surfaces, all wired through one credit ledger:
- Voices marketplace — Six character voices designed via ElevenLabs Voice Design (Detective narrator, Radio ID host, Newsreader cold, Tavern keep, Corporate PR voice, Outlaw gunslinger). Each is previewable, buyable for 25 credits, then usable for unlimited TTS in Studio.
- Packs marketplace — Music, SFX, and Ambient packs across creator listings. Browsable by category with a filter sidebar. Priced in credits. Instant unlock on purchase.
- Studio — Voice Design (text-to-voice with 3 preview picks), Instant Voice Clone (IVC) from uploaded audio, a TTS composer wired to any owned voice, and pack drafts with one-click cover-art generation. Drafts autosave; trash a draft anytime.
- Library + creator dashboard — Everything you generated or bought, plus a sales view for creators (royalty earnings, draft → publish flow).
The same user can be both a buyer and a creator. The credit ledger keeps the accounting straight.
1. Sign in — Clerk handles auth. New users get 50 free trial credits (one-time).
2. Discover — Browse /voices or /browse. Voice tiles show a Gemini-generated cover, persona description, and price. Pack tiles show the same plus sample count.
3. Preview — Click any voice. The detail page has a floating play button that streams the R2-hosted MP3 preview. Pack detail pages preview the first sample.
4. Buy with credits — Click Buy for 25 ⚡. Credits are debited, ownership is recorded in VoiceAccess / Purchase rows, the buyer is redirected to Studio or Library.
5. Out of credits? Top up. — /credits shows four Stripe-backed top-up tiles: 50 / 200 / 500 / 1000 credits ($3 → $30, volume-discounted). One click → Stripe Checkout → return to /billing/success → balance refreshes within ~2 s.
6. Use the voice — Owned voices land in the Studio TTS composer (/studio/tts?voiceId=…). Type any text, get a per-call MP3 served from ElevenLabs eleven_flash_v2_5. 1 credit per ≤5 min of output.
7. Subscribe (optional) — Creator ($9/mo) tops up 200 credits monthly. Pro Studio ($29/mo) tops up 1000 monthly. Both roll over unused credits. Stripe billing portal at /billing/portal.
8. Publish your own — Studio → New voice → Voice Design OR Instant Voice Clone. Save to private library, or mark for marketplace, set a price, publish. Buyers' purchases pay you 70 % royalty in credits (Stripe Connect cash payout is on the roadmap).
| Feature | Description |
|---|---|
| Voice Design | Describe a voice in plain English. Get 3 ElevenLabs-generated previews. Pick one. Permanent voice_id minted, preview MP3 uploaded to R2, Voice row created. |
| Instant Voice Clone | Drop 30–60 s of audio (or record in-browser). One call to /v1/voices/add and you have a voice clone ready for TTS. |
| TTS composer | Pick any voice you own, type up to 5 min of text, get a per-call MP3 streamed back. Owned across browsers via the Library. |
| Credit top-ups | Stripe Checkout for four pack sizes (50 / 200 / 500 / 1000 credits). Webhook-driven ledger entry, idempotent on Stripe retries. |
| Subscriptions | Creator $9/mo (+200 credits, rollover) and Pro Studio $29/mo (+1000, rollover). First cycle granted on checkout.session.completed; renewals on invoice.paid skip the create-cycle to avoid double grants. |
| Cover-art generation | One click on any pack draft → Gemini 3.1 Flash Image generates a 1024×1024 PNG, uploaded to R2, set as pack.cover_art_url. |
| Cart checkout | Multi-item pack checkout (Stripe payment mode) with embedded items manifest in session metadata; webhook recreates Purchase rows server-side. |
| Library | One view that merges everything: voices you own (created or bought), packs you created, packs you bought. Deduped, badged, sorted. |
| Creator dashboard | Sales, draft count, published count. Trash a draft with one hover-revealed button — published packs are protected from delete (Purchase FK is RESTRICT). |
| No-Docker dev loop | ./start.sh boots backend and frontend off the same .env.local. No Redis. No queue worker. |
Creator submits prompt + persona hints
→ POST /v1/text-to-voice/design { voice_description, auto_generate_text=true }
→ 3 previews returned: { generated_voice_id, audio_base_64 } // ElevenLabs charges once for all 3
→ creator picks preview #N
→ POST /v1/text-to-voice { generated_voice_id, voice_name, voice_description }
→ permanent eleven_voice_id minted (consumes 1 custom voice slot)
→ base64 audio decoded → uploaded to R2 voices/{voice_id}/preview.mp3
→ Voice row inserted (clone_kind=design, training_status=ready, is_private=true)
→ optional: publish-as-asset → is_private=false → listed on /voices
Failure modes refund credits and clean up the ElevenLabs voice slot.
Creator uploads N audio files (≤25 MB each, ≤50 MB total)
→ POST /v1/voices/add (multipart: name + files + labels)
→ ElevenLabs returns voice_id + requires_verification flag
→ source files archived to R2 voices/{voice_id}/source/{idx}-{filename}
→ Voice row inserted (clone_kind=ivc, training_status=ready)
→ 10 credits debited; refunded on any failure
PVC (Professional Voice Cloning) is gated behind a "coming soon" badge in the UI — see Coming Soon.
Buyer opens /studio/tts?voiceId={id}
→ frontend preselects voice from URL param
→ buyer types text, hits Generate
→ backend: confirm VoiceAccess row OR Voice.creator_id == buyer
→ debit 1 credit per ≤5 min of output (ceil)
→ POST /v1/text-to-speech/{voice_id}
model_id=eleven_flash_v2_5, voice_settings.stability=0.45
→ MP3 streamed back, uploaded to R2 (caller-owned audio)
→ audio_url returned, played inline
Creator clicks Generate cover (one-shot)
→ image_service.generate_pack_cover(pack_id, title, category, description, tags, moods)
→ category-flavoured prompt assembled (noir for sfx, etc.)
→ Gemini 3.1 Flash Image → 1024×1024 PNG
→ PNG written to backend/static/images/packs/{pack_id}.png (debug copy)
→ PNG uploaded to R2 covers/{pack_id}.png
→ pack.cover_art_url = R2 public URL
The local static path is a debug aid; the marketplace always serves from R2 so cross-origin loads from Vercel work cleanly.
Every monetisation path runs through the same signed stripe.Webhook.construct_event boundary. Each event is keyed on event.id in the processed_events table for idempotency. All money lives in test mode.
| Surface | Stripe mode | Webhook event | Outcome |
|---|---|---|---|
| Credit top-up checkout | payment |
checkout.session.completed with metadata.kind=credit_topup |
CreditLedger row +N (reason topup), idempotent |
| Subscription checkout | subscription |
checkout.session.completed (no kind) |
User tier set, first cycle credits granted via grant_monthly |
| Monthly renewal | (recurring) | invoice.paid (billing_reason != subscription_create) |
Tier-matched credits ADDED on top (rollover) |
| Subscription update | (portal) | customer.subscription.updated |
Tier + tier_expires_at reconciled |
| Cancellation | (portal or API) | customer.subscription.deleted, invoice.payment_failed |
Downgrade to free, clear tier_expires_at |
| Pack cart checkout | payment |
checkout.session.completed with metadata.kind=marketplace_cart |
One Purchase row per line item, recovered from server-side manifest |
| Billing portal | n/a | n/a | Stripe-hosted self-serve for plan / card management |
The webhook endpoint is POST /stripe/webhook. Locally, point Stripe CLI at it:
stripe listen --forward-to http://localhost:8000/stripe/webhookThe signing secret rotates every stripe listen invocation — paste it into STRIPE_WEBHOOK_SECRET in .env.local after each restart.
Five ElevenLabs surfaces are wired into production:
| Endpoint | Model / API | Where Used |
|---|---|---|
| Voice Design — preview | POST /v1/text-to-voice/design (eleven_multilingual_ttv_v2) |
Studio voice-design wizard — generates 3 voice previews from a prompt |
| Voice Design — save | POST /v1/text-to-voice |
Claims a preview, mints a permanent voice_id (consumes 1 custom voice slot) |
| Instant Voice Clone | POST /v1/voices/add (multipart) |
One-shot voice clone from uploaded audio samples |
| TTS | POST /v1/text-to-speech/{voice_id} (eleven_flash_v2_5) |
Buyer's owned voices in the Studio TTS composer |
| SFX + Ambient | POST /v1/sound-generation (eleven_text_to_sound_v2) |
Studio one-shot sample generation for SFX and looping ambient beds |
| Music | POST /v1/music (music_v1) |
Studio music-pack track generation |
Voice IDs are never hardcoded; the six seeded marketplace voices live in Voice.eleven_voice_id columns populated by app.scripts.seed_designed_voices (+ app.scripts.add_outlaw_voice). Model IDs are centralised in backend/app/config.py.
| Plan / pack | Price | Credits | Notes |
|---|---|---|---|
| Free trial | $0 | 50 (one-time) | Granted on first sign-in via grant_trial, idempotent |
| Top-up: small | $3 | 50 | $0.060 / credit |
| Top-up: standard | $9 | 200 | $0.045 / credit |
| Top-up: bulk | $18 | 500 | $0.036 / credit |
| Top-up: studio | $30 | 1000 | $0.030 / credit · cheapest per-credit rate |
| Creator subscription | $9/mo | +200/month | Same rate as $9 top-up · rollover · dashboard analytics |
| Pro Studio subscription | $29/mo | +950/month | Within ~5% of $30 top-up rate · rollover · priority queue · bundles |
Voice purchase: 25 credits each. TTS usage: 1 credit per ≤5 min of audio output. Pack purchases: creator-set, currently 5–150 credit range.
Creator royalty: 70 % of every purchase, credited to the seller's CreditBalance. Stripe Connect cash payouts are on the roadmap.
| Category | Technology |
|---|---|
| Frontend framework | Vite 5.4 + React 18.3 + TypeScript 5.9 strict |
| Styling | Tailwind CSS 3.4, Framer Motion 11, custom design tokens |
| State + data | Zustand 4 (client state), TanStack Query 5 (server state), WaveSurfer.js 7 (audio viz) |
| Frontend auth | @clerk/clerk-react |
| Backend framework | FastAPI 0.115 on Python 3.12, uvicorn 0.32 |
| ORM + migrations | SQLAlchemy 2.0 + Alembic 1.13, psycopg 3 (sync) |
| Audio processing | pydub 0.25 + ffmpeg (server-side mastering, mixing) |
| Auth verification | clerk-backend-api (JWT verify in app.deps.CurrentUser) |
| Payments | Stripe Python SDK 10.x — Checkout (payment + subscription), webhooks, billing portal |
| Voice + audio AI | ElevenLabs (eleven_multilingual_ttv_v2, eleven_flash_v2_5, eleven_text_to_sound_v2, music_v1) |
| Image AI | Google Gemini 3.1 Flash Image (1:1 covers), OpenAI gpt-image-2 (16:9 hero plates) |
| LLM helpers | Anthropic claude-sonnet-4-6 (copy + audit), OpenAI gpt-4o-mini (prompt enhancement) |
| Database | Neon Postgres 16 (managed serverless) |
| Object storage | Cloudflare R2 (S3-compatible) via boto3 1.35 |
| Frontend deploy | Vercel (root dir frontend, SPA rewrites) |
| Backend deploy | Railway (nixpacks + pip-installed requirements.txt) |
| Tests | pytest 9 + pytest-asyncio + pytest-httpx (330+ backend tests), Vitest 2 + React Testing Library + Playwright (165+ frontend tests) |
| Lint / format | Ruff + Black (Python), Biome (TS) |
| Package managers | uv (backend), pnpm 10 workspaces (frontend + shared) |
Home — hero search + 6-category deck
Home — featured pack + trending shelf
Packs marketplace — /browse
Voices marketplace — /voices
Studio — /studio
Library — /library
Creator dashboard — /creator
Pricing — /pricing
- Node 20+ and pnpm 10
- Python 3.12 and
uv ffmpeg(for pydub audio processing)- A Stripe test-mode account + the Stripe CLI
- API keys (see Environment Variables)
# At repo root
pnpm install
cd backend && uv sync && cd ..
cp .env.example .env.local
# Fill in keys (see below)./start.shstart.sh loads the root .env.local, spawns uvicorn on :8000 (with --reload) and Vite on :5173. Hit Ctrl-C to stop both.
stripe listen --forward-to http://localhost:8000/stripe/webhookCopy the printed whsec_… into STRIPE_WEBHOOK_SECRET in .env.local and restart the backend (start.sh).
# Backend: 330+ tests
cd backend && uv run pytest
# Frontend: 165+ tests
pnpm --filter frontend test# App
APP_ENV=development
CORS_ORIGINS=http://localhost:5173
# Database (Neon in prod, sqlite locally if unset)
DATABASE_URL=postgresql://...
DATABASE_URL_SYNC=postgresql://...
# Auth — Clerk (dev keys for hackathon)
CLERK_SECRET_KEY=sk_test_...
CLERK_JWT_ISSUER=https://<your>.clerk.accounts.dev
CLERK_JWT_AUDIENCE= # optional
VITE_CLERK_PUBLISHABLE_KEY=pk_test_...
# Payments — Stripe (test mode)
STRIPE_SECRET_KEY=sk_test_...
STRIPE_WEBHOOK_SECRET=whsec_...
STRIPE_PRICE_CREATOR=price_... # $9/mo recurring
STRIPE_PRICE_PRO_STUDIO=price_... # $29/mo recurring
STRIPE_SUCCESS_URL=http://localhost:5173/billing/success
STRIPE_CANCEL_URL=http://localhost:5173/billing/cancel
# AI providers
ELEVENLABS_API_KEY=sk_...
ANTHROPIC_API_KEY=sk-ant-...
GEMINI_API_KEY=...
OPENAI_API_KEY=sk-...
# Cloudflare R2 (S3-compatible)
R2_ACCOUNT_ID=...
R2_ACCESS_KEY_ID=...
R2_SECRET_ACCESS_KEY=...
R2_BUCKET=multiverse
R2_PUBLIC_BASE_URL=https://pub-<hash>.r2.dev
# Frontend
VITE_API_BASE_URL=http://localhost:8000backend/app/config.py is the source of truth for backend keys; the file lists every option with its default.
# Inside backend/ with the venv active
uv run python -m app.scripts.seed_designed_voices # 5 ElevenLabs voices (real API calls)
uv run python -m app.scripts.generate_voice_covers # Gemini covers → R2
uv run python -m app.scripts.generate_pack_images # Gemini pack covers → R2Each seed script is idempotent and skips already-seeded rows.
| Layer | Host | Config |
|---|---|---|
| Frontend | Vercel — https://multiverse-audio.vercel.app |
Root dir frontend, SPA rewrites in frontend/vercel.json, build via pnpm --filter frontend build |
| Backend | Railway — https://multiverse.up.railway.app |
Root dir backend, nixpacks python312 + ffmpeg, pip install --require-hashes -r requirements.txt, uvicorn from /opt/venv/bin/ |
| Database | Neon Postgres | Pooled connection; URL in DATABASE_URL |
| Object storage | Cloudflare R2 | Public bucket multiverse; CORS allow Vercel origin |
| Stripe webhook | Stripe dashboard → destination → https://multiverse.up.railway.app/stripe/webhook |
Events: checkout.session.completed, invoice.paid, customer.subscription.updated, customer.subscription.deleted, invoice.payment_failed |
| Auth | Clerk dev keys (hackathon) | No production domain config needed for dev instance |
Frontend env: VITE_API_BASE_URL + VITE_CLERK_PUBLISHABLE_KEY.
Backend env: everything in Environment Variables plus CORS_ORIGINS=https://multiverse-audio.vercel.app and prod-pointed STRIPE_SUCCESS_URL / STRIPE_CANCEL_URL.
Regenerate backend/requirements.txt after dependency changes:
cd backend && uv export --no-dev --no-emit-project --format requirements-txt -o requirements.txt- Radio packs — Full in-world FM broadcasts: DJ + bed + ads stitched into a single 4-minute block. Category card is in the deck with a "Coming soon" badge.
- Broadcast packs — Hour-long themed broadcast blocks (idents, ad reads, news beds).
- Professional Voice Clone (PVC) — ElevenLabs PVC takes 24–72 h to train; the studio's PVC tile is disabled with a "Coming soon" badge while we wire async polling + R2 sample archival.
- Stripe Connect Express — Creators currently accrue 70 % royalties in credits. Connect onboarding + payouts will let them withdraw cash.
- Bundle Stripe checkout — Bundles are credits-only today; cash purchase parity with packs lands next.
Licensed under the MIT License.
Built by Limb for ElevenHacks 2026.