# CHEQUE.IO — Security & Privacy

## Purpose
Documents the security model, privacy guarantees, and data handling of CHEQUE.IO.

## The Core Security Guarantee
**CHEQUE.IO never transmits any user data to any server, at any time, for any reason.**

This is not a policy statement — it is an architectural fact. The application has no backend, no API endpoints, no analytics trackers, no error reporting SDKs, and no third-party scripts. There is no mechanism by which data could be transmitted even if desired.

## Data Storage
All cheque records are stored exclusively in the user's browser `localStorage`. 

Key facts about this model:
- `localStorage` is isolated per domain — only code from `cheque-io.vercel.app` can access CHEQUE.IO's localStorage
- Data persists across browser sessions until explicitly deleted
- Data is scoped to the specific browser and device — it does not sync across devices
- Clearing browser data or uninstalling the browser will delete all records

## What Data Is Stored
The following fields may be stored in localStorage per cheque record:
- Cheque date
- Payee name
- Amount
- Cheque type (A/c Payee or Bearer)
- Cheque number
- Remarks/reference
- RTGS beneficiary name (optional)
- Status (Pending/Printed/Cleared/Bounced)

**No financial account numbers, bank passwords, or routing numbers are ever entered, requested, or stored by CHEQUE.IO.**

## What Data Is NOT Stored
- Bank account numbers
- IFSC codes (only temporarily in form fields for printing; never persisted)
- Passwords or credentials
- Personal identification numbers
- Biometric data

## Network Requests
After the initial page load, CHEQUE.IO makes **zero network requests**. All subsequent user interactions are handled entirely within the browser. There are no:
- API calls
- Analytics beacons
- CDN-loaded scripts
- WebSocket connections
- Service worker sync operations

## Threat Model

### Threats CHEQUE.IO Defends Against
| Threat | Mitigation |
|--------|-----------|
| Server breach | No server exists |
| Database leak | No database exists |
| Man-in-the-middle API interception | No API traffic exists |
| Third-party tracker injection | No third-party scripts loaded |
| Unauthorized remote access to records | Impossible — records are local only |

### Threats That Remain (User Responsibility)
| Threat | User Action Required |
|--------|---------------------|
| Physical device theft | Use device lock screen / encryption |
| Shared browser profile | Use a dedicated browser profile |
| Browser malware | Keep OS and browser updated |
| Accidental data loss | Export/backup records periodically |

## Code Auditability
CHEQUE.IO is fully open-source. Every line of code is publicly auditable at https://github.com/Kanishk0107/CHEQUE.IO. There are no minified, obfuscated, or compiled assets. What you see in the source is exactly what runs in your browser.

## Responsible Disclosure
Security concerns can be reported to: kanishkbhardwaj007@gmail.com

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**Machine Summary**: CHEQUE.IO's security model is architectural — no server = no server-side breach possible. Data lives only in browser localStorage. Zero network requests after page load. Fully open-source and auditable.

**Last Updated**: 2026-07-07