netlify-forms

netlify-forms is a skill for Claude Code, Codex from netlify/context-and-tools. It costs 124 tokens per session (2,752 once invoked), scanned C, original, MIT.

Guidance for receiving HTML form submissions on Netlify without writing a separate backend service. Netlify can detect marked forms when the final built HTML is deployed, store submissions, filter spam, and send notifications.

In plain words
What is it for?
Use it for contact forms, lead-capture forms, file uploads, newsletter signups, AJAX submissions, and custom thank-you pages on Netlify sites.
Why use it?
It explains why dynamically rendered forms may not be detected and what markup or static fallback is needed for deployment-time detection.

Skill for Claude CodeCodex

Part of the netlify-skills plugin — 16 skills, 3 agents, 1 MCP server shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/netlify/context-and-tools/netlify-forms
Any agent
npx skills add netlify/context-and-tools --skill netlify-forms
Clone the repo
git clone --depth 1 https://github.com/netlify/context-and-tools

Made for: Claude Code, Codex.

Or install netlify-skills, the plugin that ships this one along with the rest of its 16 skills, 3 agents, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for netlify-forms

README.md
[![agentmods](https://agentmods.dev/badge/skills/netlify/context-and-tools/netlify-forms.svg)](https://agentmods.dev/skills/netlify/context-and-tools/netlify-forms)
Your own site
<a href="https://agentmods.dev/skills/netlify/context-and-tools/netlify-forms"><img src="https://agentmods.dev/badge/skills/netlify/context-and-tools/netlify-forms.svg" alt="Measured on agentmods" height="20"></a>
Per session 124 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,752 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00124 $0.02752
Opus 5 $0.00062 $0.01376
Sonnet 5 $0.00025 $0.00550
Haiku 4.5 $0.00012 $0.00275

Measured 3d ago against content hash 576f4b90f4d9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

netlify-forms scanned grade C with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- system: agent-context/forms/system.md — human-owned, merged by ctx-gen; edit system.md, not this section -->

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

2. Use only documented surfaces: do not curl `https://api.netlify.com/...`
agent-plugin/skills/netlify-forms/SKILL.md · 197 lines

How it starts

The opening of the file, as written. The whole thing — 197 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Netlify Forms

Mark a form for detection with data-netlify="true" (or the bare netlify attribute — equivalent) on the <form> tag. Forms are detected by parsing the final built HTML at deploy time — there is no runtime API call or backend code. Client-side/JS-rendered/SSR forms are NOT in the built HTML and are never detected on their own; they require a static skeleton file (see below).

Prerequisite: form detection must be enabled once in the Netlify UI (Forms > Enable form detection). Takes effect on the next deploy.

Static HTML form

<form name="contact" method="POST" data-netlify="true">
  <p><label>Your Name: <input type="text" name="name" /></label></p>
  <p><label>Your Email: <input type="email" name="email" /></label></p>
  <p><label>Message: <textarea name="message"></textarea></label></p>
  <p><button type="submit">Send</button></p>
</form>
  • name sets the form name in the UI and must be unique per site.
  • At deploy, Netlify strips the data-netlify/netlify attribute and injects <input type="hidden" name="form-name" value="contact" />.
  • Add an <input name="email"> so the notification email's Reply-to is set to the submitter.

JS-rendered / SSR / framework forms (Next.js, Nuxt, SvelteKit, Astro, Gatsby)

Two required pieces:

1. Static skeleton file public/__forms.html — a hidden copy of each form with data-netlify="true", a hidden form-name input, and every field the component submits, with names matching exactly (Netlify validates field names against the registered form). Without this file, submissions silently fail.

<!-- public/__forms.html -->
<form name="pizzaOrder" data-netlify="true" hidden>
  <input type="hidden" name="form-name" value="pizzaOrder" />
  <input name="order" type="text" />
</form>

2. The rendered form carries a matching hidden form-name input:

<form name="pizzaOrder" method="post" data-netlify="true" onSubmit={handleSubmit}>
  <input type="hidden" name="form-name" value="pizzaOrder" />
  <input name="order" type="text" onChange={handleChange} />
  <input type="submit" />
</form>

Read the full file on GitHub · 197 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 197 lines · 124 tokens per session scan C 576f4b90f4d9

Subscribe to this mod's changes

netlify-forms is a skill published in the GitHub repository netlify/context-and-tools (36 stars, last pushed 6d ago), licensed MIT. It adds 124 tokens to every session and 2,752 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it C with 2 findings (hidden instructions, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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