Formatters & Code
Power BI Theme JSON Validator
Validate Power BI theme JSON files against official Microsoft schemas locally. Pinpoint invalid properties, check contrast, and test version compatibility.
Theme JSON & target version
Drag and drop your Power BI theme .json file here
or click to browse from your device · up to 10 MB
Validation Findings & Diagnostics
Color Palette & WCAG Accessibility Contrast
Evaluates data colours against canvas backgrounds. WCAG AA requires 4.5:1 for body text and 3:1 for graphical UI elements.
Results
What the result means
Power BI custom themes control report colours, fonts, and visual formatting through JSON. Ordinary JSON linters only verify brackets and commas, but Power BI Desktop enforces strict Microsoft Draft 7 schemas on import. This validator evaluates your theme against Microsoft's official schemas, pinpointing exact property paths, missing theme names, invalid hex color codes, and deprecated visual settings. It diagnoses the known Power BI export bug where solid visual colours are exported in a flattened format that Power BI itself rejects upon re-import. The built-in accessibility checker calculates WCAG 2.1 contrast ratios between your data colours and backgrounds, while cross-version testing verifies backward compatibility across monthly Power BI Desktop releases.
Related tools
Guides
Questions
Why does Power BI Desktop fail to import a theme that was just exported from another report?
Power BI Desktop's export feature sometimes serializes visual color properties with flattened structures like `color: { solid: "#ffffff" }`. However, Power BI Desktop's import validation enforces the strict Draft 7 schema, requiring `{ color: { solid: { color: "#ffffff" } } }`. This tool detects and safely corrects that exact export flaw.
What causes the "The theme file couldn't be imported" error in Power BI?
Common causes include missing the required root `name` property, invalid hexadecimal color values, unrecognized visual properties under `visualStyles`, or properties introduced in newer Power BI Desktop versions being imported into an older installation.
How does schema validation differ from ordinary JSON syntax checkers?
General JSON validators only verify that syntax is syntactically well-formed (valid braces, brackets, and quotes). They cannot determine whether property names, hierarchy, color patterns, and visual definitions match the specifications expected by Power BI Desktop's rendering engine.
Does my theme data leave the browser during validation?
No. All parsing, schema checks, color contrast audits, and safe transformations occur locally in your browser using JavaScript and pre-bundled Microsoft schemas. No data is transmitted to external servers.