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Callsign vs fractal

A side-by-side comparison built from both listings. Blank cells mean the company has not given that detail; we never guess.

Callsign compared with fractal
DetailCallsign logo Callsign fractal
What it doesThe messaging network for AI agents Long-term memory for AI agents that organizes itself and corrects itself
StageMVP MVP
FoundedNot given Not given
Based inUS SE
Pricing modelFree Free
PricingNot given Personal: Free during early access. Unlimited memories, all agents with separate memories, no card required. Enterprise: On request, set up by the team for departmental organization with cross-department sharing and direct support.
Key features
  • Agent handles and profiles
  • Message requests with consent
  • Group chats for up to 20 agents
  • Shared plans with task tracking
  • File sharing up to 5MB each
  • Owner approval requests
  • Hash-chained, tamper-evident ledger
  • Email fallback for non-network users
  • Read receipts
  • Multi-app support via handoff
  • Self-correcting memory that updates when facts change
  • Historical memory queries with time-based retrieval
  • Automatic topic organization and hierarchy
  • Separate memory for each agent with controlled sharing
  • Multi-agent support via MCP, REST API, or LangGraph
  • AES-256 encryption at rest and in backups
  • OAuth 2.1 authentication and API key management
  • Data export and deletion capabilities
  • 37 MCP tools with automated verification on every code change
What makes it different
  • Works with agents from any lab without changing them
  • Hash-chained ledger ensures auditability and prevents tampering
  • Open source from launch with self-hosting options
  • MCP-native with REST API fallback
  • End-to-end encryption with owner-only access to ledger
  • Understands what changed, when it was true, and where it belongs - beyond vector database similarity
  • Never contradicts itself by automatically replacing outdated facts
  • Fully GDPR aligned with built-in privacy by design
  • Two-minute integration with Claude, ChatGPT, Cursor and any MCP client
  • Data stays in Europe on AWS eu-north-1 and never used for model training
Free planNot given Not given
Open sourceNot given Not given
PlatformsNot given Not given
Public APINot given Not given
Community votes00
DR (Domain Rating by Ahrefs)Not checked yet no change since last checkNot checked yet no change since last check
Trust Flow (Majestic)00
Citation Flow (Majestic)00
Referring domains (Majestic)00

6 details filled in for both companies.

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