Last Updated: November 21, 2025
Zero-Knowledge Principles
End-to-end encryption (E2EE)
Data encrypted on device, decrypted only by recipient
Server has no access to decryption keys
Provider cannot read your data
Client-side encryption
Encryption happens on user's device
User controls encryption keys
Only user can decrypt their data
No plaintext on servers
All stored data is encrypted
Forward secrecy
Past communications secure even if keys compromised
Open source & auditable
Code publicly verifiable for security
Metadata minimization
Limit collection of usage metadata
Password-protected encryption
Strong password required for decryption
Zero-knowledge architecture
Provider has zero knowledge of user data
ProtonMail Features
End-to-end encrypted email
Emails encrypted between ProtonMail users
Zero-access encryption
Proton cannot read your emails
Password-protected emails to non-users
Send encrypted emails to anyone
Swiss privacy laws
Based in Switzerland with strong privacy protections
Open source clients
Web, iOS, Android apps are open source
Self-destructing messages
Set expiration time for emails
PGP support
Compatible with PGP/GPG encryption
Custom domains
Use your own domain with ProtonMail
Anonymous signup
No personal information required
ProtonCalendar & ProtonDrive
Encrypted calendar and cloud storage
Tor access via onion site
Access via .onion for extra privacy
Signal Features
Signal Protocol encryption
Industry-leading E2EE protocol
Perfect forward secrecy
Each message has unique encryption key
Encrypted voice & video calls
End-to-end encrypted communications
Disappearing messages
Messages auto-delete after set time
Screen security
Block screenshots in sensitive chats
Safety numbers verification
Verify encryption keys with contacts
Sealed sender
Hide sender identity from server
Open source & audited
Fully open source, regularly audited
No ads or trackers
Nonprofit foundation, no business model
Group messaging E2EE
Encrypted group chats up to 1000 members
Encrypted backups
Cloud backups are encrypted
Minimal metadata
Stores minimal user information
Tresorit Features
Zero-knowledge cloud storage
Encrypted file storage and sync
Client-side encryption
Files encrypted before upload
Encrypted file sharing
Share files with E2EE links
Collaboration tools
Team workspaces with encryption
Compliance certifications
ISO 27001, GDPR, HIPAA compliant
File versioning
Encrypted version history
Remote wipe
Revoke access to shared files
Activity tracking
Monitor file access (encrypted metadata)
Desktop & mobile sync
Sync across all devices securely
Admin controls
Enterprise management features
Cryptomator Features
Client-side encryption for cloud
Encrypt files for any cloud provider
Open source & free
Free for personal use, auditable code
Works with Dropbox, Google Drive, OneDrive
Compatible with major cloud services
AES-256 encryption
Industry-standard encryption algorithm
Transparent encryption
Access files like normal folders
File name encryption
Even filenames are encrypted
Mobile apps available
iOS and Android support
No account required
Local encryption, no signup
Multiple vaults
Create separate encrypted folders
Password-based key derivation
Strong password generates encryption key
Standard Notes Features
Encrypted note-taking
Zero-knowledge note storage
Cross-platform sync
Encrypted sync across devices
100% open source
All code publicly available
Extensions ecosystem
Markdown, code editor, spreadsheet editors
Offline-first
Works without internet connection
Version history
Encrypted note history
Tags & organization
Organize notes with tags (encrypted)
Two-factor authentication
Extra layer of account security
Daily backups
Automatic encrypted backups
Self-hosting option
Host your own sync server
Bitwarden Features
Zero-knowledge password manager
Encrypted password vault
Open source
Fully auditable code
End-to-end encryption
AES-256 bit encryption
Browser extensions
Chrome, Firefox, Safari, Edge support
Mobile & desktop apps
Cross-platform availability
Password generator
Create strong random passwords
Secure notes & files
Store encrypted notes and attachments
Two-factor auth support
TOTP, YubiKey, Duo integration
Self-hosting available
Host your own Bitwarden instance
Vault health reports
Weak password detection
Emergency access
Grant trusted contacts emergency access
VeraCrypt Features
Full disk encryption
Encrypt entire drives or partitions
Container volumes
Create encrypted virtual drives
Hidden volumes
Plausible deniability with hidden encrypted volumes
Multiple encryption algorithms
AES, Serpent, Twofish, or combinations
Open source
Based on TrueCrypt, fully auditable
Cross-platform
Windows, macOS, Linux support
On-the-fly encryption
Automatic encryption/decryption
Keyfiles support
Use files as additional authentication
Pre-boot authentication
Encrypt system drive, authenticate before boot
Portable mode
Run from USB without installation
App Comparison
ProtonMail vs Gmail
E2EE vs server-side scanning
Signal vs WhatsApp
Minimal metadata vs Facebook integration
Tresorit vs Dropbox
Zero-knowledge vs server access to files
Bitwarden vs LastPass
Open source vs proprietary, both E2EE
Standard Notes vs Evernote
E2EE vs server-side indexing
Cryptomator vs native cloud encryption
Client-side vs provider-controlled keys
Free tier availability
Signal, Bitwarden, Cryptomator fully free
Business vs personal use
Tresorit for teams, Signal for personal
Convenience vs maximum security
Trade-offs between usability and paranoia
Open source preference
Signal, Bitwarden, Cryptomator, Standard Notes
Security Best Practices
Use strong unique passwords
20+ character passphrases recommended
Enable two-factor authentication
Add second layer of security
Verify safety numbers (Signal)
Confirm encryption keys with contacts
Regular backups
Backup encrypted data securely
Use recovery codes
Store account recovery codes safely
Avoid password reuse
Unique password for each service
Keep software updated
Install security updates promptly
Beware of phishing
Verify URLs and sender identities
Use secure devices
Encryption only as secure as device
Understand limitations
No tool provides absolute security
When to Use Zero-Knowledge Apps
Sensitive communications
Medical, legal, financial discussions
Confidential documents
Business secrets, personal records
Journalism & activism
Source protection, whistleblowing
Government surveillance concerns
Authoritarian regimes, privacy advocates
HIPAA/GDPR compliance
Legal requirements for data protection
Personal privacy preference
Simply value privacy and control
Reducing data breach impact
Encrypted data useless if servers hacked
Avoiding targeted ads
Prevent data mining for advertising
Long-term data security
Data remains secure years later
Multi-party trust issues
Don't trust provider, ISP, or government
Pro Tip:
Zero-knowledge encryption is only as strong as your password. Use a password manager like Bitwarden to generate and store strong unique passwords. Remember: if you lose your password, not even the service provider can recover your data - that's the point of zero-knowledge!