Open-source harness
Free
Apache-2.0; inference/infrastructure separate
- Included scope
- CLI and libfx; configurable models/tools
fx by Vercel
● Identity checkedEmbeddable native coding agent · Official-source review 2026-10-09
fx is a small Zig coding-agent harness and CLI with shell-like output. Apache-2.0 source, libfx embedding and WebAssembly support let developers supply models, tools, skills and MCP connections in local or browser environments.
- Category
- Embeddable native coding agent
- Free access
- Apache-2.0 open-source harness; inference, subscriptions and infrastructure may have separate costs.
- API access
- libfx SDK embedding, configurable tools, MCP and a command-line ask interface are advertised.
Is fx by Vercel right for you?
A good fit for
Relevant to developers researching a minimal model-agnostic agent harness for custom systems.
Before you choose
Current v0.0.13 is explicitly experimental with frequent changes. Browser demo requires WebAssembly JSPI support and uses a browser workspace, rather than full access to local files. Local install provides a larger tool suite. The 6.74MiB binary size is version-specific; context/performance benefits were not independently benchmarked. Model license, provider authentication and sandbox controls remain separate. No setup script or autonomous coding run was executed.
Workflow and handoff
Inspect the official distribution, run in a disposable workspace and verify tool/network scopes before embedding it into a product.
Pricing and practical limits
Current v0.0.13 is explicitly experimental with frequent changes. Browser demo requires WebAssembly JSPI support and uses a browser workspace, rather than full access to local files. Local install provides a larger tool suite. The 6.74MiB binary size is version-specific; context/performance benefits were not independently benchmarked. Model license, provider authentication and sandbox controls remain separate. No setup script or autonomous coding run was executed.
Review method
Official product evidence reviewed on 2026-10-09; product artwork inspected visually. No hands-on vendor application test was performed. Application performance, security claims and plan enforcement were not independently tested.
What it can do
Features & capabilities
Unknown is different from unavailable. Each fact carries its own evidence.
| Capability | Value | Evidence | Checked |
|---|---|---|---|
| Product workflow | fx is a small Zig coding-agent harness and CLI with shell-like output. Apache-2.0 source, libfx embedding and WebAssembly support let developers supply models, tools, skills and MCP connections in local or browser environments. | Facts sourced | 2026-10-09 |
| Pricing and restrictions | Current v0.0.13 is explicitly experimental with frequent changes. Browser demo requires WebAssembly JSPI support and uses a browser workspace, rather than full access to local files. Local install provides a larger tool suite. The 6.74MiB binary size is version-specific; context/performance benefits were not independently benchmarked. Model license, provider authentication and sandbox controls remain separate. No setup script or autonomous coding run was executed. | Facts sourced | 2026-10-09 |
Understand the total cost
fx by Vercel pricing & plans
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Explore toolThe practical questions
Frequently asked questions
Was the application hands-on tested?
No. This listing is based on dated official-source evidence and a visual artwork check. Unconfirmed costs and restrictions are identified explicitly.
What is fx by Vercel used for?
fx is a small Zig coding-agent harness and CLI with shell-like output. Apache-2.0 source, libfx embedding and WebAssembly support let developers supply models, tools, skills and MCP connections in local or browser environments.
Does fx by Vercel have a free plan?
Apache-2.0 open-source harness; inference, subscriptions and infrastructure may have separate costs.. This record lists ongoing free access; check the plan limits before starting.
How much does fx by Vercel cost?
No paid monthly price is listed; this record treats the product as free to start. See the plan cards for entitlements, billing commitments and seat minimums.
Can I use fx by Vercel through an API?
libfx SDK embedding, configurable tools, MCP and a command-line ask interface are advertised.. API access and subscription access may have different terms; consult the linked sources.
What should I check before choosing it?
Current v0.0.13 is explicitly experimental with frequent changes. Browser demo requires WebAssembly JSPI support and uses a browser workspace, rather than full access to local files. Local install provides a larger tool suite. The 6.74MiB binary size is version-specific; context/performance benefits were not independently benchmarked. Model license, provider authentication and sandbox controls remain separate. No setup script or autonomous coding run was executed.
Price history
No retained pricing changes yet. A current price alone does not establish a historical trend.
How this profile is supported
Official product information
Current official product source read individually; product artwork inspected visually.
Read original source ↗Pricing review
Official product page reviewed for disclosed costs; unverified prices and allowances are identified in the listing.
Read original source ↗Facts apply to the named version and check date. Send a sourced correction if something changed.