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YAML Formatter

Reformat and validate YAML with consistent indentation.

Best for: Editing a CI workflow, a Compose or Kubernetes manifest, or any app config, and confirming it parses before you commit.

Complete guide

Input

How it's calculated & sources
The YAML Formatter uses the standard, deterministic formula, so the same inputs always produce the same result. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is YAML Formatter?
A YAML formatter tidies and validates YAML — the indentation-based configuration format used by CI pipelines, Docker Compose, Kubernetes and many app configs — highlighting indentation and syntax errors.
Why does YAML Formatter matter?
Consistent indentation that parses cleanly means the file is valid; an error usually points to a tab, a misaligned line, or a value that needs quoting.
How is YAML Formatter calculated?
YAML uses significant whitespace: nesting is shown by spaces (never tabs). The formatter normalises indentation and checks the structure of mappings, sequences and scalars. YAML is a superset of JSON, so any valid JSON is also valid YAML.
What are common yaml formatter mistakes?
Indenting with tabs — YAML forbids them; use spaces.
When should you use the YAML Formatter?
Editing a CI workflow, a Compose or Kubernetes manifest, or any app config, and confirming it parses before you commit.

What is the YAML Formatter?

A YAML formatter tidies and validates YAML — the indentation-based configuration format used by CI pipelines, Docker Compose, Kubernetes and many app configs — highlighting indentation and syntax errors.

How the YAML Formatter works

YAML uses significant whitespace: nesting is shown by spaces (never tabs). The formatter normalises indentation and checks the structure of mappings, sequences and scalars. YAML is a superset of JSON, so any valid JSON is also valid YAML.

Key terms

Mapping:
Key/value pairs, like a JSON object.
Sequence:
An ordered list, written with leading - dashes.
Scalar:
A single value: string, number, boolean or null.
Anchor / alias:
& defines a reusable node; * references it to avoid repetition.

Common mistakes to avoid

  • Indenting with tabs — YAML forbids them; use spaces.
  • Inconsistent indentation between sibling keys.
  • Unquoted values that look like other types: yes/no/on/off parse as booleans, and 3.10 loses its trailing zero — quote them when you mean a string.
  • Missing the space after a colon (key:value should be key: value).

Keywords: yaml, format, pretty.

Sources: YAML 1.2 Specification

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the YAML Formatter free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the YAML Formatter?+

YAML Formatter uses the standard yaml formatter formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The YAML Formatter runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the YAML Formatter on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Title: I built/used this free yaml formatter — instant, no signup

Body: Reformat and validate YAML with consistent indentation. Try it: https://freetoolsgalaxy.com/tools/yaml-formatter
LinkedIn post
YAML Formatter on Free Tools Galaxy — Reformat and validate YAML with consistent indentation. https://freetoolsgalaxy.com/tools/yaml-formatter
Medium intro
# YAML Formatter — the free tool I keep coming back to

Reformat and validate YAML with consistent indentation.

Try it: https://freetoolsgalaxy.com/tools/yaml-formatter
Quora answer
The fastest way is to use a free in-browser yaml formatter: https://freetoolsgalaxy.com/tools/yaml-formatter. Reformat and validate YAML with consistent indentation.

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<iframe src="https://freetoolsgalaxy.com/tools/yaml-formatter?embed=1" title="YAML Formatter" loading="lazy"
  style="width:100%;height:600px;border:0;border-radius:16px;background:#0b1020"
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<p><a href="https://freetoolsgalaxy.com/tools/yaml-formatter" target="_blank" rel="noopener">Powered by YAML Formatter on Free Tools Galaxy</a></p>
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<div style="position:relative;padding-bottom:75%;height:0;overflow:hidden;border-radius:16px">
  <iframe src="https://freetoolsgalaxy.com/tools/yaml-formatter?embed=1" title="YAML Formatter" loading="lazy"
    style="position:absolute;inset:0;width:100%;height:100%;border:0" allow="clipboard-write"></iframe>
</div>
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Paste in a custom-HTML block or markdown file.
[YAML Formatter — free online tool](https://freetoolsgalaxy.com/tools/yaml-formatter)

<iframe src="https://freetoolsgalaxy.com/tools/yaml-formatter?embed=1" width="100%" height="600" frameborder="0"></iframe>
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<a href="https://freetoolsgalaxy.com/tools/yaml-formatter" target="_blank" rel="noopener">Try the free YAML Formatter</a>

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