Validate YAML Syntax & Find Errors Instantly (Line-Level Check)
Validate YAML syntax instantly in your browser. Get real-time feedback on errors with exact line and column numbers. Supports multi-document YAML and shows document statistics including nesting depth and key counts.
How to Use YAML Validator
How to Use the YAML Validator:
Paste Your YAML: Type or paste your YAML content into the input area. Validation happens in real-time as you type — no button press needed.
Read the Status Banner: A green "Valid YAML" banner means your YAML is syntactically correct. A red "Invalid YAML" banner means there is an error.
Fix Errors: When invalid, the error card shows the exact line number, column number, and error message. Use these to locate and fix the issue in your YAML.
Review Document Statistics: When valid, the statistics panel shows line count, top-level keys, total keys, maximum nesting depth, and document count.
Use Examples: Click the example buttons (App Config, Docker Compose, GitHub Actions, Invalid Demo) to load sample YAML and explore how the validator works.
Clear: Click the Clear button to reset the input and start fresh.
Common YAML Errors and Fixes:
- Tabs instead of spaces: YAML requires spaces for indentation — never tabs. Your editor may silently insert tabs.
- Inconsistent indentation: All sibling keys must be at the same indentation level. YAML is whitespace-sensitive.
- Unclosed quotes: A string starting with a quote must end with the matching quote on the same logical line.
- Colon without space: In a mapping, the colon must be followed by a space (key: value, not key:value).
- Special characters in values: Values containing colons, curly braces, or square brackets should be quoted.
- Duplicate keys: YAML technically allows duplicate keys but behavior is undefined — most parsers use the last value.
Common Use Cases:
- Validating Docker Compose files before running docker-compose up
- Checking GitHub Actions workflow syntax before pushing
- Verifying Kubernetes manifests before applying them
- Debugging Ansible playbooks and Helm chart values
- Validating configuration files for frameworks like Rails, Django, and Spring Boot
Frequently Asked Questions
Most Viewed Tools
TOTP Code Generator
Generate time-based one-time passwords from a TOTP secret key. Enter your base32 secret, choose a period and digit length, and get the current and next codes with a live countdown timer. Useful for testing and debugging 2FA integrations.
Use Tool →JSON to Zod Schema Generator
Generate Zod validation schema code from a JSON sample object. Infers z.string(), z.number(), z.boolean(), z.array(), z.object(), and z.null() types automatically. Handles nested objects, arrays of objects with optional field detection, and outputs copy-ready TypeScript with import and z.infer type alias.
Use Tool →JSONL / NDJSON Formatter
Format, validate, and inspect JSON Lines (JSONL) and NDJSON files. Validates each line individually, reports parse errors by line number, outputs compact JSONL or a pretty-print preview, and lets you download the cleaned file.
Use Tool →Secret and Credential Scanner
Scan pasted text, code, or config files for accidentally exposed API keys, tokens, passwords, and private keys. Detects 50+ secret types across AWS, GitHub, Stripe, OpenAI, and more — all client-side, nothing leaves your browser.
Use Tool →TLS Cipher Suite Checker
Check TLS protocol version compatibility and cipher suite strength ratings against current best practices. Supports IANA and OpenSSL cipher names — rates each suite as Strong, Weak, or Deprecated and explains why.
Use Tool →Password Entropy Calculator
Calculate the information-theoretic bit entropy of any password or API key. Detects character set pools automatically, shows the total number of possible combinations, and estimates crack time across five attack scenarios from rate-limited web logins to GPU cracking clusters.
Use Tool →TOML Config Validator
Validate TOML configuration file syntax and report errors with line numbers. Paste any TOML content — Cargo.toml, pyproject.toml, config.toml — and instantly see a green checkmark with key counts and structure stats, or a precise error message pointing to the exact line. Includes a collapsible JSON structure preview to confirm what was parsed.
Use Tool →Content Security Policy Generator
Build Content Security Policy headers interactively. Toggle directives like script-src, style-src, and img-src, select allowed source tokens, and add custom origins. Instantly outputs your CSP as an HTTP header, meta tag, Nginx directive, or Apache header.
Use Tool →Related DevOps & Infrastructure Tools
Query String Parser
Parse URL query strings into readable key-value pairs. Decode parameters and inspect URL search queries with ease.
Use Tool →API Response Formatter
Format and beautify API responses for better readability. JSON formatter with minify and prettify options.
Use Tool →SSL Certificate Validator
Paste a PEM certificate to instantly validate expiry, signature algorithm, key strength, SAN presence, and trust chain. Get a clear pass/warn/fail report for each check.
Use Tool →Cookie Parser
Parse HTTP cookie strings into readable key-value pairs. Decode URL-encoded values and inspect cookies from browser requests.
Use Tool →Cron Expression Validator
Validate cron expressions, get a plain-English explanation of what they mean, and see the next scheduled run times — all in your browser.
Use Tool →robots.txt Validator
Validate your robots.txt file against the Robots Exclusion Protocol. Checks directive syntax, path formats, Crawl-delay values, and Sitemap URLs. Previews crawl rules per user-agent group. Free and runs entirely in your browser.
Use Tool →Sitemap Validator
Validate XML sitemaps against the sitemap protocol specification. Checks structure, required fields, URL count, changefreq values, and priority ranges. Supports both URL sitemaps and sitemap index files. Free and runs entirely in your browser.
Use Tool →HTTP Header Analyzer
Parse and analyze HTTP request or response headers. Identifies categories, explains each header, flags missing security headers, and detects duplicates or suspicious values — entirely in your browser.
Use Tool →Share Your Feedback
Help us improve this tool by sharing your experience