Causal vs Praex: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of Causal and Praex — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
Causal
Causal Software Limited
An infinite AI canvas for creative planning, where notes, files, images and links sit in one spatial workspace an agent can read and build on.
Key features
- Infinite Spatial Canvas: A freeform, unbounded board where notes, images, links and files are arranged by meaning, so layout itself becomes the organisation rather than a folder hierarchy.
- Context-Aware Agent: The AI reads the whole canvas and understands how ideas connect, then answers questions and researches topics with the surrounding board as context.
- Native Output Generation: Prompts are turned into canvas content directly, with the agent creating notes, files and web-link cards and placing them where they belong instead of returning plain text.
- Rich File Previews: PDFs, Word and Adobe documents, markdown, spreadsheets, images and video up to 20 MB open fullscreen in-app, and markdown and CSV files can be edited in place and saved back to the file.
- Dual Text Editing: Quick notes live directly on the canvas while longer pieces open into a full-page editor, both sharing headings, lists, checkboxes, quotes, code blocks, highlights, images and links.
- Structure Tools: Collections pack related nodes into tidy columns, nested canvases give a sub-topic its own space, and an unsorted tray parks anything not ready to be placed.
- One-Click Sharing: Any canvas becomes a read-only link that recipients open without an account, covering nested canvases too, and sharing can be revoked at any time.
- Template Library: Ready-made boards for app flows, app plans, brand research, branding boards, competitor research, onboarding, storyboards, video briefs and plans, website moodboards and website plans.
Best for
- Product Planning: Map every screen in an app and the routes between them, then keep features, screens and shipping order in one view instead of three separate documents.
- Brand Development: Collect the brands, palettes and voices you are borrowing from, then settle type, colour and marks in one place the whole team works from.
- Competitive Research: Put rival products side by side with your own on a single board and find the gap you can actually take.
- Video and Film Pre-Production: Block out a shoot frame by frame, hand an editor references, tone and deliverables on one canvas, and follow a video from script to final cut with every asset attached to its step.
- Website Design Prep: Gather reference sites, type and colour a build should feel like, then lay out every page and its contents before the first component is built.
- Team Onboarding: Walk a new starter through the tools, files and people one frame at a time on a shareable board.
Praex
Praex
Open-source AI coding copartner with its own Velox, Faber and Lucia models, available in terminal, mobile and web.
Key features
- Own Model Family: Velox II, Faber II and Lucia II are tuned and served by Praex on its own infrastructure, sized from quick edits to frontier-scale problems.
- Terminal CLI: Install with a one-line script and let the agent read files, run commands, edit code and verify tests directly in your terminal.
- Cross-Device Sessions: Start a task in the terminal, steer it from your phone and review it on the web with the same agent, memory and session.
- Bring Your Own Keys: Run Praex on any model with your own API keys or hardware at no extra cost.
- Open-Source Core: The CLI is an MIT-licensed fork of opencode, so the agent harness can be inspected and modified.
- No Sign-Up Chat: Start chatting on the web with the free Velox II model without creating an account.
Best for
- Fixing Failing Builds: Hand the agent a broken deploy and let it read configs, run tests and patch source until tests pass.
- Everyday Quick Edits: Use the free Velox II model for instant answers and small code changes in the terminal.
- Deep Reasoning Tasks: Escalate to Faber II on Pro for complex coding and multi-step reasoning.
- Mobile Task Steering: Kick off a refactor at your desk and monitor or redirect it from your phone.
- Self-Hosted Workflows: Point the CLI at your own models or keys to keep code on infrastructure you control.