Content Digest

Paste a link (article, YouTube, Instagram, Facebook, TikTok, X, or a direct audio file) and get a summary, key takeaways, a category, and tags. The front end is Next.js. The n8n workflow in workflow.json does the extraction and the AI work.

The browser calls app/api/digest/route.ts, which forwards the request to N8N_WEBHOOK_URL. n8n is never called from the client.

Webhook contract

POST {N8N_WEBHOOK_URL} with Content-Type: application/json

{ "url": "https://www.youtube.com/watch?v=..." }

Success (200)

{
  "id": "29",
  "status": "ok",
  "type": "text",
  "url": "https://...",
  "data": {
    "title": "string",
    "summary": "string (2-4 paragraphs separated by blank lines)",
    "keyTakeaways": ["string"],
    "tags": ["lowercase", "strings"],
    "category": "Technology | Business | Science | Health | Politics | Education | Entertainment | Lifestyle | Sports | Other",
    "language": "ISO 639-1 code",
    "source": { "platform": "youtube | instagram | facebook | tiktok | x | media | article", "method": "transcript | article", "truncated": false },
    "wordCount": 1234
  }
}

Error (4xx/5xx): { "status": "error", "message": "Human-readable reason" }

Code	When
400	Missing or invalid URL
404	Video not found
422	No transcript or readable text (private, paywalled, no speech)
429	Supadata or Jina rate limit
500 / 502	AI or upstream service failure
504	Async transcription took longer than about 2 minutes

Typical response times: articles take 5–30 s, captioned videos 10–40 s, and videos without captions (AI transcription) up to about 2 minutes.

How the workflow works

1. Classify URL (Code node): validates the URL and picks a branch.
2. Videos and social posts go to the Supadata /v1/transcript?mode=auto endpoint, which uses existing captions or falls back to AI transcription. Long videos return 202 { jobId }; the workflow then polls every 5 s, up to 24 times.
3. Direct audio files go to the Gemini "Transcribe a Recording" node.
4. Everything else is treated as an article and read with Jina Reader (r.jina.ai), which returns clean markdown.
5. Check Content: rejects text shorter than 80 characters and trims anything over 120k characters.
6. Summarize: a Basic LLM Chain using Gemini gemini-3.6-flash with a structured output parser. If that model fails, it falls back to gemini-3.5-flash-lite.

id is the n8n execution ID. It matches the requestId column in the backend history table.

History

• Browser: every successful digest is saved to localStorage under content-digest:history:v1, up to 50 entries. Summarizing the same URL again replaces its old entry. The History drawer reopens a saved digest without calling n8n, and lets you delete one entry or clear them all. This history lives only in the user's browser. See lib/history.ts.
• n8n: after the webhook responds, Prepare History Row passes every request, successful or failed, to Save to History, which writes it to the n8n Data Table digest_history. Columns: requestId, status, url, platform, method, title, category, tags, summary, keyTakeaways (JSON string), language, wordCount, httpStatus, errorMessage, plus the automatic createdAt. The save runs after the response and continues on error, so it never slows down or breaks a request. When you import workflow.json on another instance, create this table first and re-select it in Save to History.

Credentials needed in n8n

• Header Auth with name x-api-key and your Supadata key. Used by Supadata Transcript and Supadata Job Status.
• Google Gemini (PaLM) API. Used by Gemini Chat Model, Gemini Fallback Model, and Gemini Transcribe.

When you import workflow.json, re-select these credentials on each of those nodes. Credential IDs are stripped from the export.

Local development

cp .env.example .env.local   # point N8N_WEBHOOK_URL at your n8n webhook
npm install
npm run dev                  # http://localhost:3000

Deployment notes

• The API route sets maxDuration = 300 and gives n8n up to 180 s to respond.
• On Vercel, N8N_WEBHOOK_URL must be a publicly reachable URL, either n8n Cloud or a tunnel to your local n8n. localhost won't work.