Is the match case-sensitive?

No, matching is case-insensitive, so a keyword of 'update' also matches paragraphs containing 'Update' or 'UPDATE'.

What does the invert option do?

It flips the filter to keep only the paragraphs that do NOT contain the keyword, instead of the ones that do.

How are paragraphs detected?

The text is split on blank lines (one or more empty lines between blocks of text), and each resulting block is treated as one paragraph.

Paragraph Filter Online - Keep or Remove Matching Paragraphs

Overview

Introduction

Scanning a long document for the paragraphs that discuss a specific topic, or specifically excluding paragraphs that do, is slow to do by eye.

This tool automates it with a single keyword and an invert toggle.

What Is Paragraph Filter?

A paragraph filter that keeps (or, with the invert option, discards) every paragraph containing your keyword, matched case-insensitively, and rejoins the result with a blank line between each surviving paragraph.

It runs entirely client-side as part of this site's String Tools collection, so nothing you paste is ever uploaded to a server.

How Paragraph Filter Works

The input is split into paragraphs on blank lines, and each paragraph is tested for whether it contains the keyword (lowercased for a case-insensitive comparison); matching paragraphs are kept or discarded depending on the invert toggle, then rejoined with blank lines.

The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.

When To Use Paragraph Filter

Use it to pull every paragraph mentioning a topic out of a long document, or to strip out paragraphs matching an unwanted pattern before publishing.

It's a fast way to get the answer without opening a code editor, a REPL, or writing a one-off script just to check.

Often used alongside String Line Filter and Sentence Filter.

Features

Advantages

Case-insensitive by default, matching common expectations for quick text search.
Invert option covers both 'keep matches' and 'remove matches' use cases.

Limitations

Paragraph detection relies on blank lines between blocks, so text without blank-line separation is treated as a single paragraph.

Examples

Keeping paragraphs containing 'pricing'

Input

Intro paragraph about the product.

This paragraph covers pricing details.

A closing paragraph with no keyword.

Output

This paragraph covers pricing details.

Only the paragraph containing 'pricing' is kept; the others are dropped.

Best Practices & Notes

Best Practices

Use Sentence Filter instead if you need finer-grained filtering within a paragraph rather than keeping or dropping it as a whole.

Developer Notes

Paragraphs are split with `/\n\s*\n/`, the same heuristic used elsewhere in this site's paragraph-based tools, then matched with a lowercased `String.prototype.includes()` check.

Paragraph Filter Use Cases

Pulling every paragraph mentioning a topic out of a long document
Removing paragraphs matching an unwanted keyword before publishing
Quickly scanning a pasted document for relevant sections

Common Mistakes

Pasting text without blank lines between paragraphs; the filter then treats the whole input as one paragraph.

Tips

Use the invert toggle to quickly flip between 'show matches' and 'hide matches' without retyping the keyword.

Paragraph Filter