YAML Formatter
Format YAML.
How do you format and validate YAML online?
Docuboxer's YAML formatter fixes indentation, aligns nested structures and validates the syntax of YAML documents directly in your browser — nothing you paste is sent to any server. YAML runs half of modern infrastructure — docker-compose files, Kubernetes manifests, GitHub Actions workflows, Ansible playbooks — and it is unforgiving: hierarchy is defined entirely by indentation, so a single misplaced space silently changes the structure or breaks the parse. Paste your file here and the formatter normalizes the indentation while the validator flags syntax errors, duplicate keys and structural problems before they reach a deploy. Because processing happens in your device's memory, configs containing secrets, tokens or internal hostnames never leave your machine, and the tool keeps working offline once the page has loaded. Free, no signup, no data retention.
How to use YAML Formatter
- Paste your messy YAML or load a .yaml/.yml file from your device.
- The formatter fixes the indentation, aligns nested structures and validates the document's syntax.
- Copy the formatted YAML to the clipboard or download the corrected file, ready to use in your project.
Common use cases
Edit Docker and Kubernetes config files
Format and validate docker-compose.yml, Kubernetes deployments, Ansible playbooks and any infrastructure-as-code file to avoid the indentation errors that cause failed deploys.
Check CI/CD pipelines and GitHub Actions
Make sure your .github/workflows files, GitLab CI configs and other continuous-integration YAML are structurally correct before pushing to the repository.
Debug a YAML file that won't parse
When an application rejects your config with a cryptic parse error, paste the file here to see exactly where the syntax breaks.
Normalize YAML written by different hands
Bring files edited by several teammates — or generated by different tools — to a consistent indentation style before review.
Validate configs with secrets safely
YAML files often carry tokens, connection strings and internal hostnames. Here they are processed only in your browser — never uploaded.
Frequently asked questions
How do I validate a YAML file online?
Paste the YAML (or load the file) and the validator checks it instantly, flagging syntax errors and pointing at the problem. Everything runs locally in your browser — free, no signup, nothing uploaded.
Why is indentation so critical in YAML?
YAML uses indentation — spaces, never tabs — to define the data hierarchy. A single wrong space can completely change the structure of the document or cause parsing errors in the applications that read it.
Does the validator catch duplicate keys?
Yes. It identifies duplicate keys at the same level, inconsistent data types, circular references and other structural problems that could cause unexpected behavior in your application.
Can I use tabs in YAML?
No — the YAML spec forbids tabs for indentation, and most parsers reject them. The formatter normalizes indentation to spaces, which fixes the most common cause of mysterious parse failures.
Does it work with docker-compose and Kubernetes manifests?
Yes. They are plain YAML, which is exactly what the tool formats and validates. It checks syntax and structure; validating Kubernetes-specific field names is the job of kubectl or your cluster's admission checks.
Is my YAML uploaded to a server?
No. Formatting and validation run entirely in your browser's memory — no server, no logs, no retention — and keep working offline once the page has loaded.