Introducing Cloak: Secure Document Sharing as an API

We're launching Cloak — an open-source API that turns any document into a secure, trackable, watermarked link. One API call to upload, one link to share, real-time analytics to track engagement.

The problem

Every day, teams share sensitive documents as PDF attachments or Google Drive links. These get forwarded, downloaded, and shared without the sender's knowledge. There's no way to know who actually read your proposal, when they read it, or if they forwarded it to a competitor.

Existing solutions like DocSend are GUI-only, expensive ($65/user/month), and impossible to integrate programmatically. If you're building a platform that needs to share documents securely — an LMS, a deal room, an investor portal — your only option was to build it yourself.

The solution

Cloak is a REST API. Upload a file, get back a tokenized secure link. Recipients view the document in a browser-based viewer with:

• + Dynamic watermarks (viewer's email on every page)
• + Email gate (verify identity before viewing)
• + Link expiry (time-based or view-count limits)
• + Page-level analytics (time per page, completion rate)
• + Canvas-based rendering (no downloads, no screenshots)
• + Webhooks (get notified when someone views your doc)

$ curl -X POST https://api.cloakshare.dev/v1/links \
    -H "Authorization: Bearer ck_live_xxx" \
    -F file=@proposal.pdf \
    -F expires_in="72h" \
    -F watermark=true

{"secure_url": "https://view.cloakshare.dev/s/lnk_xK9mP2"}

Open source

Cloak is MIT licensed and fully self-hostable. Clone the repo, run docker compose up, and you have a working document security system on your own server. No vendor lock-in.

The cloud version at cloakshare.dev adds CDN delivery, analytics dashboard, webhooks with retries, custom domains, embedded viewer, email notifications, and managed infrastructure.

Get started

Sign up for a free API key at app.cloakshare.dev. The free tier includes 50 links and 500 views per month — enough to evaluate and prototype. Or self-host for unlimited usage.

Read the documentation or check out the source code on GitHub.