---
title: "Troubleshooting: Fix Common Prettify Problems | Prettify Docs"
description: "Fix common Prettify problems: parse errors, Load from URL
  failures, large files, license activation, offline limits, and clearing data."
url: https://prettify.tools/docs/troubleshooting
---

[Docs](https://prettify.tools/docs) / Help

# Troubleshooting

Last updated: October 16, 2026

This page lists common problems in Prettify and how to fix them. Each item points to the feature that controls the behavior. If your problem is not here, report it with the bug report dialog, described at the end.

## A document will not parse

Prettify reports a parse error with its line and column in the Problems panel. Read the message, go to the line, and fix the text.

- JSON: when the syntax error is fixable, the paste dialog offers Fix all and a per-issue fix. Use it to repair trailing commas, missing quotes, and similar errors.
- Mermaid: the document must start with a diagram keyword, for example `flowchart`. See [Mermaid](https://prettify.tools/docs/mermaid).
- Markdown and MDX: a YAML frontmatter error shows with its line. An unclosed code block shows as a warning.

## Load from URL fails

Load from URL fetches a document from a web address.

On the web, Prettify fetches the URL directly first. A site that blocks cross-origin requests makes the direct fetch fail. Prettify then asks for your consent to use a public proxy, because the proxy sees the full URL. Prettify asks once per session.

If the server returns an error status, for example 404 or 500, Prettify shows that status. A proxy does not help in that case, so fix the URL.

On the desktop app, Prettify fetches in the background process, which browser CORS rules do not bind. It refuses private and local addresses.

## A file is too large

Prettify is a data viewer, not a big-file editor, so it caps sizes.

- A single file over 100 MB does not open in the desktop app.
- A URL response over 100 MB is refused.
- A Markdown or MDX file of 200 KB or larger opens in a read-only Preview. Edit it in the Raw view.

## License activation errors

Activate Pro in Settings, under License.

- You must be online to activate or deactivate. The buttons are disabled when you are offline.
- An invalid key shows "Activation failed".
- If the license is already active on the maximum number of devices, Prettify shows: "This license is already active on N of M devices. Deactivate Prettify on another device (Settings, License, Deactivate) and try again." Free a device, then activate again.
- Check your purchase email for the key. If you lost it, open your Lemon Squeezy order.

If deactivation removes the license here but cannot release the device slot, Prettify tells you. Free the slot from your Lemon Squeezy dashboard so it does not count later.

## Working offline

When you are offline, Prettify shows a banner. Open documents stay saved locally, and parsing, editing, and queries keep working.

These actions need a connection and work again after you reconnect: sharing to a short link, Load from URL, license activation and deactivation, checkout, and desktop update checks.

## Clear local data

Prettify keeps your documents and history on your device.

- Select Clear in the header to empty the current document.
- Open the [History](https://prettify.tools/docs/history) page and select Clear All to remove every saved document and version. This cannot be undone.

## Report a bug

Select Report Bug in the sidebar, or open it from the Command Palette with `Cmd+K` (Mac) / `Ctrl+K` (Windows, Linux).

Fill in a title and a description. You can add a screenshot by paste, drag, or file picker. Prettify attaches coarse context, for example the format, the view, and the app version. It never attaches your document contents. See [Privacy](https://prettify.tools/docs/privacy).

## Related

- [Desktop app](https://prettify.tools/docs/desktop-app) covers installs, updates, and offline use.
- [Sharing](https://prettify.tools/docs/sharing) explains share links.
- [Privacy](https://prettify.tools/docs/privacy) lists what Prettify sends and keeps.

## Try it online

Tool pages for this topic. Each one runs in your browser.

- [JSON Syntax Checker](https://prettify.tools/json-syntax-checker)
- [JSON Validator](https://prettify.tools/json-validator)
- [YAML Validator](https://prettify.tools/yaml-validator)

[PreviousPrettify Pro](https://prettify.tools/docs/pro)

## Structured data

```json
{
  "@context": "https://schema.org",
  "@type": "SoftwareApplication",
  "name": "Prettify",
  "url": "https://prettify.tools",
  "description": "Multi-format data viewer, editor, and query engine for JSON, YAML, CSV, XML, Mermaid, Markdown, MDX, HTML, and SVG",
  "applicationCategory": "DeveloperApplication",
  "operatingSystem": "Web, macOS, Windows, Linux",
  "offers": [
    {
      "@type": "Offer",
      "price": "0",
      "priceCurrency": "USD",
      "description": "Free tier with core features"
    },
    {
      "@type": "Offer",
      "price": "19.99",
      "priceCurrency": "USD",
      "description": "Pro: lifetime access to all features"
    }
  ],
  "publisher": {
    "@id": "https://prettify.tools/#organization"
  }
}
{
  "@context": "https://schema.org",
  "@type": "Organization",
  "@id": "https://prettify.tools/#organization",
  "name": "Prettify",
  "legalName": "Off Leash Labs",
  "url": "https://prettify.tools/",
  "logo": {
    "@type": "ImageObject",
    "url": "https://prettify.tools/icon-512.png",
    "width": 512,
    "height": 512
  },
  "contactPoint": {
    "@type": "ContactPoint",
    "contactType": "customer support",
    "email": "offleashlabs@gmail.com",
    "availableLanguage": "English"
  }
}
```