YAML Validator – Indentation & Syntax Error Checker
If a YAML configuration fails to load, check its indentation and syntax before changing application settings. Validate the exact file, review any reported line or column, and pay particular attention to nested lists, quoted values, duplicate keys, and spacing.
YAML Validator Features
Indentation level checking, duplicate key detection, and anchor validation
📐 Indentation Level Checker
Detects space vs tab indentation mismatches and key alignment errors.
⚠️ Duplicate Key Detection
Flags duplicate mapping keys within the same nesting block that silently overwrite values.
⚓ Anchor & Alias Verification
Verifies declared anchors (`&anchor`) and matching aliases (`*alias`) across configuration documents.
🔒 100% Client-Side Privacy
Validation runs in local browser RAM. Zero YAML configuration files are uploaded to servers.
Find why a YAML configuration will not load
A small indentation mistake or an incorrectly quoted value can stop a YAML configuration from being read. Paste the exact YAML or load the file to check its syntax, then use the reported error to focus your edits instead of rewriting the whole document.
1. Validate the original configuration
Paste the YAML, choose a file, or load the sample. Use the version that fails in your application so the reported location matches the real issue.
2. Check indentation and punctuation
Look around the reported line for inconsistent spaces, missing colons, unmatched quotes, or list items that are not aligned with their parent. YAML uses indentation to represent structure.
3. Correct a small area and retry
Fix the likely syntax issue and validate again. Once parsing succeeds, check whether the configuration uses the keys and values your application expects.
Valid YAML can still be an invalid configuration
A syntax validator checks whether the document can be parsed as YAML. It cannot know whether a setting name is supported by your application, whether a file path exists, or whether a value is appropriate for your deployment. If the YAML parses but the application still fails, check the application's own schema and error output.
Frequently asked questions
Why does indentation matter in YAML?
Indentation defines which values belong to a list or mapping. Inconsistent spaces can change the structure or make the document invalid.
Will this tell me whether my application settings are correct?
It checks YAML syntax, not application-specific requirements. Check your application's schema and documentation after the file parses successfully.
Frequently Asked Questions
How does the YAML Validator detect indentation errors?
The YAML Validator parses indentation spacing, key-value colon alignment, and sequence dash levels, pinpointing exact line numbers whenever tab vs space or level mismatches occur.
Is my YAML configuration safe during validation?
Yes, 100%. All YAML syntax checking, anchor/alias resolution, and file downloads run locally inside your browser's RAM memory using client-side JavaScript. Zero data is sent to external servers.
Does the tool support YAML anchors and aliases?
Yes! The validator verifies that all declared anchors (&anchor) have matching, valid aliases (*alias) throughout your configuration document.