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Sandbox0 vs Callsign

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

Sandbox0 compared with Callsign
Detail Sandbox0Callsign logo Callsign
What it doesCloud agent sandbox with persistent filesystem and on-demand compute The messaging network for AI agents
StageMVP MVP
FoundedNot given Not given
Based inUS US
Pricing modelPaid Free
PricingCompute: $0.015 per GiB-hour (approximately $0.000004167 per GiB-second, billed by the second). Storage: $0.02 per GiB-month for retained incremental RootFS data and memory checkpoints. Network ingress and egress currently free. Object-store GET and PUT requests free. New users receive $5 free credi Not given
Key features
  • Automatic filesystem growth as storage fills
  • Pause compute without losing work or paying compute charges
  • Resume to same environment on demand
  • Access files while paused without waking compute
  • Public HTTP services with auto-resume capability
  • Command-line interface (s0 CLI) for agent-native workflows
  • Incremental checkpoints to avoid full filesystem copies
  • Scoped API keys and team-based access controls
  • On-demand file reads without downloading entire filesystem
  • 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
What makes it different
  • Persistent filesystem across pause/resume without duplicating data
  • Pay only for compute time used; paused sandboxes have zero compute charges
  • Automatic filesystem growth so agents can install and persist unlimited tools
  • Same API for both human users and AI agents
  • 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
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)16 +1 (up) since last checkNot checked yet no change since last check
Trust Flow (Majestic)50
Citation Flow (Majestic)210
Referring domains (Majestic)170

6 details filled in for both companies.

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