fx vs OneCLI: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of fx and OneCLI — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
fx
Vercel Labs
Vercel Labs' tiny open-source coding agent — a ~6 MB native CLI written in Zig, built for speed, embeddability and Unix-style ergonomics.
Key features
- Tiny Native Binary: The whole agent ships as a roughly 6 MB executable designed for instant installation and for embedding in resource-constrained environments and agent sandboxes.
- Instant Time to Prompt: fx cold starts in about 10 microseconds and performs no unnecessary work or I/O before accepting user input, which matters for programmatic invocation.
- Minimal Memory Footprint: A single-digit-megabyte memory baseline lets you pack many concurrent instances onto one machine.
- Shell-Like Ergonomics: Scroll history is preserved by default and output is deliberately sparse, so the CLI composes like a Unix tool instead of taking over the terminal.
- Context Efficiency: A minimal system prompt and tool surface reduce token spend and improve time-to-first-token performance.
- WebAssembly Builds: Optimal fx.wasm builds from the Zig toolchain shrink the binary further and make the network stack pluggable, enabling the in-browser demo.
- Model and Provider Agnostic: Works with local models, LLM gateways, direct provider API access or existing subscriptions rather than locking you to one vendor.
- Extensible Small Core: Capabilities are added through skills, plugins and MCPs, following a Unix-like philosophy of a small core with composable extensions.
Best for
- Sandboxed Agent Execution: Ship a full coding agent inside a container or sandbox where a large runtime would not fit.
- Embedding in Larger Systems: Use fx as the agent harness inside your own product or internal platform rather than building a loop from scratch.
- CI and Scripted Automation: Invoke a coding agent from pipelines and scripts where fast cold starts and quiet output matter more than an interactive UI.
- Agent Harness Research: Experiment with system prompt and tool design on a deliberately minimal, readable Apache-2.0 codebase.
- Local-Model Coding: Run agentic coding against a locally hosted model without any dependency on a specific cloud provider.
- Browser-Based Demos and Playgrounds: Compile to WebAssembly and run the agent client-side with networking delegated to browser fetch.
OneCLI
OneCLI
An open-source platform giving every employee a sandboxed AI agent that reaches company tools through a credential gateway and never holds a real secret.
Key features
- Per-Request Credential Injection: The OneCLI gateway injects scoped credentials for each call so agents never hold a real secret, and keys never leave the vault.
- Isolated VM Per Employee: Every employee's agent runs in its own virtual machine, keeping one person's agent workload and data separated from everyone else's.
- Hard Policy Limits Outside the Model: Destructive actions such as deleting a repository, sending a payment or wiping a customer record are blocked by external enforcement rather than by asking the model to behave.
- Runaway Agent Circuit Breaker: An agent that starts repeating itself or acting far faster than a person would is automatically slowed or paused before it can cause damage.
- Human Approval Gates: Sensitive steps — like emailing a customer — pause with the work already prepared and wait for a team member's explicit go-ahead.
- Access Inheritance: An agent can only reach the tools and accounts its owner already has, so support cannot reach billing and nobody shares a password.
- Slack, CLI and SDK Interfaces: Employees can chat with their agent directly in Slack or drive it programmatically through the OneCLI CLI and SDK.
- Open Source with Self-Hosting: The platform is open source, and Enterprise customers can deploy it entirely inside their own infrastructure with SSO and SAML.
Best for
- Company-Wide Assistant Rollout: Give every employee an autonomous agent without handing out shared credentials or standing API keys.
- Regulated Workflow Automation: Automate finance or customer operations where certain actions must be provably impossible for an agent to take.
- Slack-Native Task Delegation: Ask an agent in Slack to complete a multi-step job across internal tools and get pinged only when a human decision is needed.
- Least-Privilege Agent Access: Scope each department's agent to that department's systems so support, engineering and billing stay in their own lanes.
- Security Review of Agent Activity: Use audit-log retention and resource-level scoping to reconstruct exactly what an agent touched and when.
- Self-Hosted Enterprise Deployment: Run the whole agent platform inside your own network with SSO, SAML and custom integrations.