Volley vs Castov

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

Volley compared with Castov
Detail	Volley	Castov
What it does	API sequence diagram tool with payloads on every arrow	Fast, 100% client-side developer platform with zero-data logging
Stage	Not given	Not given
Founded	Not given	Not given
Based in	Not given	Not given
Pricing model	Freemium	Free
Pricing	Free: editor, local diagrams, share links, SVG and PNG export, CLI, 3 saved diagrams, HAR imports up to 8 requests, 200 hosted API and MCP calls a month, 1 webhook inbox with 25 requests a month, 1 recording link with 3 recordings. Pro: $9/month or $90/year (billed in advance), up to 1,000 saved dia	All tools are free with no usage limits. The site may show ads in the future to cover running costs.
Key features	Plain-text sequence diagram editor with real-time rendering Request and response payloads displayed on every arrow HAR file import with automatic redaction of secrets Webhook inbox to capture and diagram provider deliveries Recording links to collect customer HAR files as diagrams Drift Check to update diagrams when APIs change SVG and PNG export for sharing and embedding AI agent support via MCP server, HTTP API and CLI README embeds that update when diagrams are edited Presentation mode for step-through walkthroughs	Multi-timezone support with IANA database and daylight saving time JSON to TypeScript conversion JWT decoder and inspection Cron expression parser and generator End-to-end encrypted environment variable vaults P2P multiplayer canvas with WebRTC and CRDT Steganography for hiding encrypted secrets in images Service Worker API mocker for frontend testing Encrypted URL shares with hash fragment storage
What makes it different	No account needed to write and share diagrams AI can write diagrams from plain-text syntax Built from real traffic: HAR files, webhooks and customer recordings	Zero-data logging: no keystroke sent to external servers, all processing in browser memory 100% client-side operation works entirely offline Unified ecosystem across web, CLI, and AI agents via MCP Server Sub-millisecond performance with local execution Tool chaining and piping for seamless multi-stage workflows
Free plan	Not given	Not given
Open source	Not given	Not given
Platforms	Not given	Not given
Public API	Not given	Not given
Community votes	0	0
DR (Domain Rating by Ahrefs)	3 no change since last check	1 +1 (up) since last check
Trust Flow (Majestic)	3	1
Citation Flow (Majestic)	22	19
Referring domains (Majestic)	8	7

5 details filled in for both companies.

More alternatives to Volley More alternatives to Castov