How is this different from `yq` or `prettier --parser yaml`?

Both work, but each has friction. `yq` is a CLI you need to install (Go binary or Python wrapper depending on the fork) and remember flags for. Prettier requires a Node project and a config file. This tool is a single browser page — paste, click, copy. The parser is the same `eemeli/yaml` library that powers Prettier's YAML mode, so the output matches what Prettier would produce for the same input.

Will "sort keys" break my YAML if it uses anchors or aliases?

Anchors (`&name`) and aliases (`*name`) survive: the parser resolves them into shared JS references, then sort-keys reorders map entries alphabetically by key. The structural relationship is preserved, but the textual anchor/alias names are dropped on re-serialization (the values are inlined where they were referenced). If you depend on anchor names being preserved literally, format without "sort keys" enabled.

Are comments preserved when I format?

No. Comments are dropped on re-serialization because the formatter parses to a plain JS object first, then re-emits. This matches what Prettier does for YAML. If preserving comments matters, run the formatter only on comment-free sections, or use `yq -P` locally which has a "document"-mode that keeps comments.

Why does my minified flow-style output look ugly with long lines?

That's the YAML spec, not a bug. Flow style is YAML's JSON-like inline syntax — `{key: val, arr: [1, 2, 3]}` — designed for compact transport over the wire. It's not meant to be read by humans. If you want a single-line representation that humans can scan, convert to JSON instead (use our YAML ⇄ JSON tool). For human-readable YAML, use Format with 2 or 4 space indent.

Does it support YAML 1.1 quirks like `yes`/`no` as booleans?

No — this tool follows the YAML 1.2 spec (the modern, default spec). Under 1.2, `yes`, `no`, `on`, `off` are plain strings, and only `true` / `false` (and their casing variants) are booleans. If your file targets 1.1 (e.g. older Ansible playbooks), add `%YAML 1.1` directive at the top — but better, migrate to 1.2 quoted strings, since 1.1 boolean coercion is a frequent source of production bugs.

Stop CI failing on a stray tab in a GitHub Actions workflow

A push fails with "found character that cannot start any token" on line 47 of your workflow. Someone's editor inserted a tab where YAML demands spaces. Paste the file, hit Format with 2-space indent, and the parser flags the exact line, then re-emits the whole document with spaces only. Copy it back and the run goes green.

Make Kubernetes manifests diff-stable before a review

Two engineers edit the same 300-line Deployment and the PR diff is a mess because map keys landed in different order. Turn on Sort keys and format both files: every map is reordered alphabetically, so the only lines that show up in `git diff` are the ones that actually changed, not 40 phantom reorder lines.

Validate a docker-compose file with secrets without uploading it

Your `docker-compose.yaml` holds DB passwords and an API token, so a web validator that POSTs to a server is a non-starter. This runs entirely in the tab, so you can paste the real file, confirm the indentation under `services:` parses, and fix the offending line before `docker compose up` chokes on it.

Minify a config for a curl payload or a one-line annotation

You need to stuff a small YAML config into a Kubernetes annotation or a shell variable where multi-line strings are painful. Click Minify to collapse it to single-line flow style like `{replicas: 3, image: nginx}`, paste it inline, and skip the heredoc gymnastics.

YAML Formatter & Validator — Re-indent, Lint, Minify, Sort

Format and beautify YAML — re-indent, validate, minify, sort keys.

Runs locally
Category Format Converter
Best for Turning pasted content or local files into a handoff-friendly format.

Sort keysIndent:

Input

Output

Formatted output appears here.

What this tool does

Free online YAML formatter and validator. Paste a config and get clean, consistently indented output — 2 or 4 spaces (YAML spec forbids tabs). One-click minify produces a single-line flow-style document for transport. Syntax errors are reported with line numbers from the parser (eemeli/yaml, YAML 1.2) so you can fix invalid YAML in place. Optional "sort keys" recursively reorders every map alphabetically — useful for diff-stable Kubernetes manifests and lockfiles. 100% client-side: secrets in your `.env.yaml`, Helm values, GitHub Actions workflows, and docker-compose files never leave the browser tab.

Tool details

Input: Text + Numbers + Structured content; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy + Download; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: No account required; Open the page and use it; whether results survive refresh depends on the tool.
Performance budget: Initial JS <= 25 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Format Converter · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How YAML Formatter & Validator fits into your work

Use it when the main problem is getting content from one practical format into another.

Conversion jobs

Turning pasted content or local files into a handoff-friendly format.
Previewing a conversion before you use it in a larger workflow.
Cleaning small format mismatches without opening a full editor.

Conversion checks

Try a small sample first when the source format is messy.
Check character encoding, separators, and line endings after conversion.
Keep the source until the converted output has been reviewed.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Stop CI failing on a stray tab in a GitHub Actions workflow
A push fails with "found character that cannot start any token" on line 47 of your workflow. Someone's editor inserted a tab where YAML demands spaces. Paste the file, hit Format with 2-space indent, and the parser flags the exact line, then re-emits the whole document with spaces only. Copy it back and the run goes green.
Make Kubernetes manifests diff-stable before a review
Two engineers edit the same 300-line Deployment and the PR diff is a mess because map keys landed in different order. Turn on Sort keys and format both files: every map is reordered alphabetically, so the only lines that show up in `git diff` are the ones that actually changed, not 40 phantom reorder lines.
Validate a docker-compose file with secrets without uploading it
Your `docker-compose.yaml` holds DB passwords and an API token, so a web validator that POSTs to a server is a non-starter. This runs entirely in the tab, so you can paste the real file, confirm the indentation under `services:` parses, and fix the offending line before `docker compose up` chokes on it.
Minify a config for a curl payload or a one-line annotation
You need to stuff a small YAML config into a Kubernetes annotation or a shell variable where multi-line strings are painful. Click Minify to collapse it to single-line flow style like `{replicas: 3, image: nginx}`, paste it inline, and skip the heredoc gymnastics.

Common pitfalls

Expecting comments to survive: the formatter parses to a plain object first, so a `# pinned for CVE-2024-xxxx` note disappears. Format only comment-free sections, or keep the note outside the formatted block.
Assuming Sort keys keeps anchor names: `&web` / `*web` resolve to inlined values and the textual names are dropped, so format without Sort keys if a downstream tool greps for the anchor literally.
Treating `on:` in a GitHub Actions file as safe under 1.1 habits: in YAML 1.2 it stays a string key, but in 1.1 tooling `on` can coerce to boolean true, which silently renames the key. Quote it as `"on":` to be safe.

Privacy

Everything runs in your browser tab via the eemeli/yaml library compiled to JavaScript. Your YAML is never uploaded, logged, or sent to any server, and the input is not written into the URL, so secrets in `.env.yaml`, Helm values, or docker-compose files stay local. Close the tab and nothing persists.

FAQ

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YAML Formatter & Validator — Re-indent, Lint, Minify, Sort

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How YAML Formatter & Validator fits into your work

Conversion jobs

Conversion checks

Good next steps

Real-world use cases

Stop CI failing on a stray tab in a GitHub Actions workflow

Make Kubernetes manifests diff-stable before a review

Validate a docker-compose file with secrets without uploading it

Minify a config for a curl payload or a one-line annotation

Common pitfalls

Privacy

FAQ

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