netlify-forms

netlify-forms is a skill for Codex from PracticalSwan/agent-skills. It costs 124 tokens per session (3,306 once invoked), scanned C, original, MIT.

A guide to adding forms to websites hosted on Netlify. Netlify can detect submitted HTML forms during deployment, store the entries, 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 how to make forms work without building a separate form backend, including the extra setup needed when forms are rendered by JavaScript.

Skill for Codex

Written for Codex: reads ~/.codex or $CODEX_HOME. Also seen: mentions Claude Code; mentions Codex.

Good fit Use it for contact forms, lead-capture forms, file uploads, newsletter signups, AJAX submissions, and custom thank-you pages on Netlify sites.

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Install with agentmods
npx agentmods add skills/practicalswan/agent-skills/netlify-forms
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.

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

Made for: Codex.

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/practicalswan/agent-skills/netlify-forms/github.svg)](https://agentmods.dev/skills/practicalswan/agent-skills/netlify-forms)
Your own site
<a href="https://agentmods.dev/skills/practicalswan/agent-skills/netlify-forms"><img src="https://agentmods.dev/badge/skills/practicalswan/agent-skills/netlify-forms/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for netlify-forms

Your own site · 80×15
<a href="https://agentmods.dev/skills/practicalswan/agent-skills/netlify-forms"><img src="https://agentmods.dev/badge/skills/practicalswan/agent-skills/netlify-forms.svg" alt="Reviewed on agentmods" width="80" 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 3,306 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00124 $0.03306
Opus 5 $0.00062 $0.01653
Sonnet 5 $0.00025 $0.00661
Haiku 4.5 $0.00012 $0.00331

Measured 4d ago against content hash 28e9a02e40ec, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, 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 4d 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/...`
netlify-forms/SKILL.md · 248 lines

How it starts

The opening of the file, as written. The whole thing — 248 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 · 248 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 4d ago Changed 28e9a02e40ec
  2. 6d ago Changed 5c9bb43c33c0
  3. 8d ago First seen · 248 lines · 124 tokens per session scan C 2202209c18a6

Subscribe to this mod's changes

netlify-forms is a skill published in the GitHub repository PracticalSwan/agent-skills (14 stars, last pushed 4d ago), licensed MIT. It adds 124 tokens to every session and 3,306 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 2026-09-03.

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