Keyword Highlighter

📖 Tool Introduction

Keyword Highlighter is a visual tool for locating and marking the important phrases inside long text at a glance. Whenever you read a lengthy article, review a contract clause, analyze a customer-service thread or compile search results, you often need to track where several keywords appear and in what surrounding context. This tool lets you add any number of keywords, assigns each one a distinct highlight color automatically, and marks every hit in the preview with a colored background, so the emphasis of the whole passage jumps out instantly. Multiple keywords can be supplied together by separating them with commas or spaces, or added one by one and removed individually; they are managed as colored chips that you can edit freely. Two optional switches refine the matching: case sensitivity is ideal for pinning down English proper nouns, while whole-word mode only highlights complete words so that substrings buried inside longer terms are not accidentally tagged. The preview itself is rendered with safe DOM nodes rather than by injecting markup, so even if your text contains angle brackets, scripts or raw HTML tags, they are displayed as ordinary characters and never executed as web code, which removes injection risk at the root. You can export the highlighted result as a standalone HTML file to open in a browser, or copy the original plain text in one click. A status line reports the total number of matches so you can judge how densely each keyword is distributed. All computation happens locally in your browser, which makes the tool well suited for sensitive documents such as contracts, notes and drafts that you would rather not upload anywhere. Because the preview updates the moment you add or delete a chip, iterating on your search terms feels immediate and frictionless, and the source text in the input box is never altered by the highlighting pass. The whole tool stays fully offline, so it works equally well on a slow connection and in a locked-down intranet.

✨ Key Features

• Multiple keywords: add many at once, each auto-colored
• Two options: case sensitive and whole-word, freely toggled
• Safe rendering: marks are DOM nodes, user input never runs as code
• Live preview: chips refresh the highlight the moment they change
• HTML export: download a standalone colored web page in one click
• Match counts: live totals show how each keyword distributes

📝 How to Use

1. Type a word in the keyword box and click Add or press Enter
2. Tick case sensitive and whole-word as needed
3. Paste the long text to annotate into the input area
4. Click Highlight Preview and inspect the colored marks
5. Copy the plain text or export an HTML file to share

⚠️ Notes

• Longest first: when keywords overlap at one spot, the longest wins to avoid nested marks
• Word boundaries: whole-word mode uses CJK and Latin boundaries; turn it off for continuous Chinese
• Color cycle: beyond six keywords colors repeat, but marking stays correct
• Safe export: the exported HTML escapes the source and opens safely in any browser
• Source intact: highlighting only affects the preview; the input stays plain text