Does this YAML formatter send my data anywhere?

No. Formatting runs entirely in your browser using the open-source `yaml` parser, the same library many Node.js tools rely on. Nothing you paste is uploaded, logged, or stored on a server, which matters when the document you're formatting is a Kubernetes manifest or CI config with real environment values in it.

Will formatting change my data, like key order or comments?

Key order and values are preserved exactly. Comments are the one exception: because they aren't part of YAML's data model, a full parse-and-reserialize pass drops them, the same tradeoff any YAML library makes. If your document leans on comments for documentation, keep a copy of the original before formatting.

Can it turn compact flow-style YAML into block style?

Yes. Flow-style collections like `{a: 1, b: [1, 2]}` are parsed the same as their block equivalents, so pasting flow-style input and formatting it produces indented, one-key-per-line block YAML, useful when a config was generated in its most compact form and you need to read or edit it by hand.

What happens if my YAML has a syntax error?

The formatter won't guess at malformed structure. It reports the exact line and column the parser stopped at, taken directly from the underlying parse error, so you can jump to the problem, most often bad indentation, an unquoted colon inside a value, or a tab character where YAML requires spaces.

What's the difference between the YAML Formatter and the YAML Minifier?

The formatter expands YAML into readable, indented block style; the minifier does the opposite, collapsing it into the most compact flow-style form. Both round-trip through the same parser, so neither changes the underlying data, only how it's laid out on the page.

YAML Formatter & Prettifier - Format YAML Online

Overview

Introduction

YAML's whole appeal is readability, but that promise breaks down fast once a document gets auto-generated, hand-edited by several people, or written in compact flow style. This formatter takes any valid YAML and re-lays it out with consistent indentation, so nested structure is visible at a glance.

It exists for the same reason a JSON formatter does: the tools that produce YAML (Helm, Ansible, CI pipelines) optimize for correctness, not for how the file looks when a human opens it later to debug a failing deploy.

What Is YAML Formatter & Prettifier?

A YAML formatter parses a document into its underlying data structure and re-serializes it with consistent spacing: one key per line, indentation that reflects nesting depth, and normalized list syntax.

Because YAML supports both block style (indented, one item per line) and flow style (JSON-like braces and brackets), the same data can look very different depending on who or what wrote it. Formatting normalizes that into one consistent, readable shape.

How YAML Formatter & Prettifier Works

Your input is parsed with a full YAML 1.2 parser and re-serialized in block style at your chosen indent width. Because it goes through a real parser rather than a text-based reindenter, the output is guaranteed to be valid YAML whenever the input was.

Everything happens client-side, so there's no upload step and no size limit beyond what your browser can hold in memory.

When To Use YAML Formatter & Prettifier

Use it after pulling a Helm chart's rendered values, a Kubernetes manifest exported from a dashboard, or any YAML that arrived compact or inconsistently indented.

It's also a good first step before manually editing a document, since consistent indentation makes it obvious which block a given line actually belongs to.

Often used alongside YAML Minifier, YAML Validator and YAML Syntax Highlighter.

Features

Advantages

Runs entirely client-side, so config files with real secrets never leave your browser.
Normalizes both block and flow style input into one consistent output.
Confirms the document is valid YAML as a side effect of formatting.
Configurable indent width matches your project's existing style.

Limitations

Comments are not preserved, since they fall outside YAML's data model and don't survive a parse-and-reserialize round trip.
Only the first document in a multi-document (`---`-separated) stream is formatted.
Very large files (tens of megabytes) may be slow, since the whole document is held in memory while parsing.

Examples

Flow style to block style

Input

name: api
config: {debug: false, retries: 3}

Output

name: api
config:
  debug: false
  retries: 3

The flow-style mapping is expanded into indented block style with one key per line.

Inconsistent indentation gets normalized

Input

Output

a:
  b: 1
  c:
    - 1
    - 2

Regardless of the input's indentation width, the output uses a consistent width at every level.

Bad indentation prevents formatting entirely

Invalid input

a: b
  c: d

Parser error

Nested mappings are not allowed in compact mappings at line 1, column 4:

A key indented under a scalar value isn't valid YAML, so the parser reports the exact location instead of guessing at the intended structure.

Corrected version

a: b
c: d

Best Practices & Notes

Best Practices

Format YAML before committing sample fixtures so diffs stay readable.
Match the indent width your team's editor config already uses.
Keep a copy of heavily-commented files before formatting, since comments don't survive the round trip.
Format immediately after copying a manifest out of a dashboard or CLI tool, since those often emit flow-style or minimally indented output.

Developer Notes

Internally this uses the `yaml` package's `parse()` followed by `stringify(value, { indent, lineWidth: 0 })`. Setting `lineWidth: 0` disables automatic line folding so long scalar values stay on one line rather than being wrapped, which keeps the output predictable and matches what most YAML consumers expect. No regex-based reflow is used anywhere, so the result is always parseable YAML when the input was.

YAML Formatter & Prettifier Use Cases

Cleaning up a Helm values file before code review
Reformatting a Kubernetes manifest exported from a dashboard
Normalizing indentation across YAML files from different contributors
Expanding compact flow-style config into something you can actually edit

Common Mistakes

Mixing tabs and spaces for indentation, which YAML's spec forbids inside block structure.
Assuming formatting will fix invalid YAML, when it only reformats documents that already parse.
Losing inline comments during a format-and-recopy workflow without realizing it.

Tips

Use the reported line and column to jump straight to a parse error.
Pair this with the YAML Validator when you only need a yes/no check, not reformatted output.
If you're about to edit a compact flow-style file by hand, format it first so the structure is visible.

YAML Formatter & Prettifier