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47 formatters across 4 categories — code, text, data, and more.

Start with your question

What do you need to format?

Debugging an API response?Paste raw JSON and get it indented, coloured, and readable in one click.JSON Formatter →Writing or reviewing a SQL query?Format messy single-line SQL into readable, properly indented clauses.SQL Formatter →Preparing a blog post URL?Convert any title or heading into a clean, SEO-friendly slug automatically.Text to Slug →Switching text case?Convert between camelCase, snake_case, PascalCase, kebab-case, and more in one click.Case Formatter →Fixing mixed tabs and spaces?Normalise indentation across pasted code to match your project's style guide.Tab to Space →Previewing Markdown output?Write or paste Markdown on one side and see the rendered HTML output in real time.Markdown Formatter →

Things worth knowing

Why formatting is not just cosmetic

~30 sectime saved per review

Formatting is the fastest code review win

Consistently formatted code is read faster and reviewed more accurately. A properly indented JSON blob surfaces structural issues that a flat string hides entirely. Formatting before sharing is a small habit that prevents embarrassing bugs from slipping through review.

30–40%smaller when minified

Pretty-print to read, minify to ship

A pretty-printed JSON file with whitespace and newlines is 30–40% larger than its minified equivalent. The pretty version is what you debug; the minified version is what you send in an API response or store in a config file. A formatter gives you both representations instantly.

RFC 3986the URL spec

Why slugs need more than just spaces replaced

RFC 3986 defines which characters are safe in a URL. A proper slug must be lowercase (URLs are case-sensitive on most servers), use hyphens not underscores (Google treats hyphens as word separators), strip accents and diacritics, and remove special characters entirely. A slug formatter applies all these rules automatically — replacing them by hand is error-prone.

snake vs cameltwo worlds, one copy-paste

The case mismatch that causes silent bugs

Python and SQL use snake_case; JavaScript uses camelCase; CSS uses kebab-case; Go uses PascalCase for exports. Every time you copy an identifier from one ecosystem to another, you risk a case mismatch. A case formatter eliminates that step — paste once, convert to any convention in one click.

Frequently Asked Questions

What does a JSON formatter do?

A JSON formatter takes a valid but unformatted (or minified) JSON string and adds consistent indentation, newlines, and spacing to make it human-readable. It also validates the JSON in the process — if the input is malformed, the formatter reports the parsing error and the approximate location of the problem.

Is my data sent to a server when I format it?

No. All formatting runs in your browser using JavaScript. Nothing you paste into any formatter is transmitted to a server or stored anywhere. This makes these tools safe to use with sensitive payloads like API keys, database records, or internal query results.

What is the difference between JSON formatter and JSON minifier?

The formatter adds whitespace and indentation to make JSON readable for humans. The minifier removes all non-essential whitespace to produce the smallest valid JSON string — useful for reducing payload size in API responses or config files. Both tools accept the same input; they just produce opposite outputs.

What case formats are supported by the case formatter?

The case formatter supports camelCase, PascalCase, snake_case, SCREAMING_SNAKE_CASE, kebab-case, Title Case, UPPERCASE, and lowercase. It correctly handles transitions between words even when the input is a mix of conventions — for example, converting "getUserFullName" to "get_user_full_name" without manual editing.

Can I format large SQL queries?

Yes. The SQL formatter handles queries of any length and supports standard SQL as well as dialect-specific keywords from MySQL, PostgreSQL, and SQLite. It reformats SELECT, INSERT, UPDATE, DELETE, and DDL statements, aligning keywords, indenting subqueries, and wrapping long lines at a configurable column width.

What is a URL slug and why does it matter for SEO?

A slug is the human-readable part of a URL that identifies a specific page — for example, "how-to-file-income-tax-online" in the URL example.com/blog/how-to-file-income-tax-online. Clean slugs improve click-through rates from search results, are easier to share, and help search engines understand page topics. Google recommends hyphens over underscores and lowercase letters throughout.

Does the Markdown formatter support all Markdown flavours?

The Markdown formatter renders CommonMark-compliant Markdown, which covers the vast majority of everyday usage — headings, bold, italic, lists, links, images, blockquotes, and fenced code blocks. GitHub Flavored Markdown (GFM) extensions like tables and task lists are also supported.

Can I convert tabs to spaces in bulk?

Yes. The tab-to-space formatter accepts any amount of text and converts all tab characters to a configurable number of spaces — typically 2 or 4. It also supports the reverse operation (spaces to tabs) for projects that enforce tab-based indentation. The conversion is lossless and does not affect any other whitespace.

What should I use to format code in a production pipeline?

For production pipelines, use a CLI tool — Prettier for JavaScript/TypeScript/JSON/CSS, Black for Python, gofmt for Go, or sqlfluff for SQL. Browser-based formatters like these are designed for interactive use: paste, inspect, copy. They are not a substitute for linting or formatting hooks in a CI/CD pipeline.

Do formatters change the meaning of my code?

No. A formatter only changes whitespace, indentation, and line breaks — never the tokens, identifiers, values, or structure of your code. The formatted output is semantically identical to the input. If a formatter changes meaning, that is a bug in the formatter, not expected behaviour.

About this formatter library

thecalcu.com brings together free formatters across code, text, data, and everyday use. Every formatter runs in the browser — nothing you paste is transmitted or stored — making them safe for internal data, API payloads, and confidential query results.

Code formatters cover JSON (pretty-print and minify), SQL (multi-dialect), and Markdown (CommonMark + GFM). Text formatters handle case conversion across eight conventions, URL slug generation, and line break normalisation. The tab-to-space formatter solves the universal pain of mixed indentation when pasting code across editors or programming languages.

Every formatter accepts input by paste or direct typing, produces output instantly, and includes a one-click copy button. There are no file size limits for browser-based formatting. For automated formatting in a CI pipeline, these tools complement — rather than replace — project-level tools like Prettier, Black, or sqlfluff.

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