What is YAML and what is it used for?

YAML (YAML Ain't Markup Language) is a human-readable data serialization format designed for configuration files. It uses indentation and minimal punctuation. YAML is commonly used in Docker Compose, Kubernetes, CI/CD pipelines (GitHub Actions, GitLab CI), and Ansible playbooks.

Is my data safe when using this converter?

Yes. All conversion happens 100% client-side in your browser. Your YAML data is never sent to any server, stored, or logged. There are no API calls involved in the conversion process.

How do I convert YAML to environment variables?

The To Env Vars tab flattens nested YAML keys into environment variable declarations. Choose from four output formats: .env file (KEY=VALUE), shell export (export KEY=VALUE), Docker ENV, or JSON. Nested keys are joined with a configurable separator.

What types of YAML errors can be auto-fixed?

The fixer handles BOM characters, CRLF line endings, trailing whitespace, tabs in indentation, missing colons after keys, unquoted values with special characters, inconsistent boolean/null casing, misaligned indentation, and misaligned nesting from copy-paste errors.

How does the Merge tab work?

The Merge tab deep-merges two YAML files: objects are merged recursively, arrays are concatenated, and scalar conflicts are shown side-by-side for you to pick A or B. Use the All A or All B buttons to bulk-resolve.

Encoding & Data

YAML Toolkit

Free online YAML validator and formatter. Auto-fix syntax errors, merge YAML files with conflict resolution, and convert YAML to JSON, TOML, Properties, or .env. Perfect for Docker Compose, Kubernetes manifests, CI/CD pipelines, and Ansible playbooks. 100% client-side, no data uploaded.

Open tool

Quick reference

Category: Encoding & Data
Runs in: Browser
Data stored: Nothing
Price: Free
Sign-up: Not needed

Browse categories

All features

Syntax validation with line/column error reporting
Auto-fix for 9 common YAML error types
Two-file merge with conflict resolution
Convert to JSON, TOML, Properties, or .env
Reformatting, beautification, and key sorting
Drag-and-drop upload and download output

What you can do

Validate YAML syntax

Paste YAML and instantly see syntax errors with exact line and column positions. Catches indentation issues, missing colons, and tab characters.

Auto-fix common errors

The Fix tab automatically repairs 9 common YAML problems: BOM, CRLF, trailing whitespace, tabs, missing colons, unquoted specials, and inconsistent casing.

Merge two YAML files

Deep-merge two YAML files with recursive object merging, array concatenation, and conflict resolution with side-by-side A/B selection.

Convert to JSON, TOML, or Properties

Transform YAML configuration to JSON for APIs, TOML for Rust/Python projects, or Java Properties with dot-notation flattening.

Generate environment variables

Convert YAML config to .env files, shell exports, Docker ENV, or JSON with configurable separators and array handling.

Reformat and sort keys

Beautify YAML with consistent indentation or sort all keys alphabetically for normalized diffs and deterministic output.

Private by design

Client-side
No sign-up
Free

YAML Toolkit runs entirely in your browser tab. No data is uploaded, no server processes your input, and no account is required.

Specifications

Standard: YAML 1.2 (anchors, aliases, multi-line strings)
Conversion targets: JSON, TOML, Java Properties, .env/.sh/Docker/JSON
Auto-fix types: 9 (BOM, CRLF, tabs, colons, quoting, casing, indent)
Merge strategy: Deep merge with A/B conflict resolution
File support: Drag-drop upload, download converted output
Processing: 100% client-side, works offline

Frequently asked questions

Related keywords

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