Validate and convert JSON, YAML, XML, CSV and JWT, without uploading a byte
Paste a config, a payload or a token. It is checked as you type, and every error points to its line and column. 29 free tools, all running in your browser.
- No signup
- No upload
- Works offline once loaded
All tools
Validate
Find the exact line and column, not just "invalid".
- JSON ValidatorStrict RFC 8259 check with line:column errors and duplicate-key warnings.
- YAML ValidatorIndentation, tabs, duplicate keys, multi-document files.
- XML ValidatorWell-formedness check: unclosed tags, bad attributes, line:col.
- CSV ValidatorColumn counts, unclosed quotes, duplicate headers, blank rows.
- JSON Schema ValidatorCheck data against a schema; draft a schema from a sample.
Format
Readable in one paste. Or squashed for transport.
Convert
Every direction between JSON, YAML, XML, CSV and TOML.
- YAML to JSONConvert YAML (Kubernetes manifests, CI workflows, OpenAPI files) to JSON.
- JSON to YAMLConvert JSON to clean, readable YAML with 2 or 4 space indentation.
- JSON to CSVTurn a JSON array of objects into CSV for Excel, Google Sheets or a database import.
- CSV to JSONConvert CSV to a JSON array of objects using the header row as keys, or to an array of arrays.
- XML to JSONConvert XML to JSON with control over the mapping: attribute prefix, text key, and whether repeated elements always become arrays.
- JSON to XMLConvert JSON to well-formed XML.
- CSV to XMLConvert CSV rows into XML records.
- XML to CSVFlatten XML into a CSV table.
- XML to YAMLConvert XML to YAML, for example to turn a Maven pom or an old config file into something easier to read and edit..
- YAML to CSVConvert a YAML list of mappings into a CSV table, for example a list of hosts, users or feature flags..
- CSV to YAMLConvert CSV rows into a YAML list of mappings using the header row as keys: handy for fixtures, Ansible inventories and seed data..
- TOML to JSONConvert TOML (Cargo.toml, pyproject.toml, Hugo and Netlify config) to JSON.
- JSON to TypeScriptInfer interfaces from a sample API response.
Tokens & encoding
Decode what is inside, verify who signed it.
Query & compare
Find the value, or find what changed.
Why "line 3, column 12" beats "invalid JSON"
Most validators stop at a yes or no. Every checker here reports where the parser gave up and what it expected instead, highlights the line, and jumps your cursor there. When the cause is not obvious, one optional click asks an AI model to explain the mistake and propose a corrected document, which is re-checked before you use it.
Each tool page also explains the part of the format that trips people up: why a missing comma is reported on the next line, why YAML reads NO as false, when a CSV field needs quotes, how XML attributes land in JSON, and why a JWT can be read by anyone but forged by no one.
Private by construction
Config files contain hostnames, tokens contain user IDs, CSV exports contain customers. None of it should go to a stranger's server just to add some indentation. Here the parsing libraries are downloaded once and run on your machine; open the network tab and watch nothing leave. Details are on the privacy page.