URL: /rules/reliability

---
title: "Reliability audit rules: broken scripts, fonts and forms"
sidebarTitle: "Reliability"
description: "Audit rules for what fails to load: scripts, stylesheets and fonts that return errors, and forms whose fields or actions lose submissions."
---

Reliability rules check that what a page asks the browser to load actually loads, and that a form's submission reaches a handler. They read the scripts, stylesheets and fonts the crawl already fetched, so a bundle that returns 404 after a deploy shows up even when the HTML that references it is a 200. The category sits in the Performance score group, since a page whose main script never loads is slow to become usable, and the rules need no browser render.

## Run only these rules

```bash
squirrel audit https://example.com --rule-include reliability
```

Reliability and [Performance](/rules/perf) make up the Performance score group. Run both with `--rule-include perf,reliability`.

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## Where to start

These carry the highest severity and weight in the category.

- [Broken scripts, stylesheets and fonts: files that do not load](/rules/reliability/broken-resources): A page whose script or stylesheet returns 404 or 500 looks fine to a crawler but renders unstyled or never runs its interactive parts. squirrel checks every script, stylesheet and font the crawl fetched.
- [Forms that lose submissions: unnamed fields and dead actions](/rules/reliability/broken-forms): A form can look perfect and still drop every submission. squirrel checks that each field has a name the browser sends, and that each form action answers.

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## Rules

| Rule | What it flags | Severity | Scope |
|---|---|---|---|
| [Broken scripts, stylesheets and fonts: files that do not load](/rules/reliability/broken-resources) | A page whose script or stylesheet returns 404 or 500 looks fine to a crawler but renders unstyled or never runs its interactive parts. squirrel checks every script, stylesheet and font the crawl fetched. | error | Site-wide |
| [Forms that lose submissions: unnamed fields and dead actions](/rules/reliability/broken-forms) | A form can look perfect and still drop every submission. squirrel checks that each field has a name the browser sends, and that each form action answers. | error | Site-wide |

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## Key terms

- [HTTP status code](/glossary/http-status-code): The three-digit code a server returns with every response; 2xx success, 3xx redirect, 4xx client error, 5xx server error.

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## Related categories

[Performance](/rules/perf) covers how fast the same resources load. [Images](/rules/images) checks image sources, and [Links](/rules/links) checks link targets that return errors.

## Learn more

- [Fix SEO issues with AI](https://squirrelscan.com/learn/fix-seo-issues-with-ai), the coding agent workflow for working through a report
- [Website audit tool](https://squirrelscan.com/tools/website-audit)
- [Sample report](https://squirrelscan.com/reports/squirrelscan-sample), with the Reliability section on a real site

## Disable all Reliability rules

```toml squirrel.toml
[rules]
disable = ["reliability/*"]
```