Syntax Checker & Linter Studio

What does a syntax checker do?

A syntax checker reads source code and reports structures that the selected language parser cannot understand: an unfinished expression, a missing delimiter, malformed markup or an invalid configuration value. A linter adds selected rules for likely mistakes and code quality. Syntax Checker & Linter Studio brings these tasks into a tabbed workspace so you can inspect a snippet, a configuration file or several independent files before returning to your editor.

Open text files or paste code into a new tab. The filename suggests a language, and an explicit language selection takes precedence. Check one file or the complete workspace, then filter the Problems panel by severity and select a result to move to its line and column. Live checking waits briefly after typing. Each file keeps its own editor history, while the combined report helps you review the workspace without repeatedly switching between tabs.

Understand the coverage for each language

The 60 language modes do not all promise the same checks. JavaScript and JSX use ESLint with selected rules, Python uses Ruff, and TypeScript provides syntax diagnostics with optional standalone type checking. Data and web formats use their respective parsers or validators. Many additional languages use Tree-sitter grammars to identify unexpected or missing syntax nodes. The capability panel names the actual engine and distinguishes structural syntax checking from linting, formatting and available fixes.

A clean check means that this checker detected no issues within its stated coverage. It does not establish that a project builds, that imports exist or that code is safe to execute. TypeScript files are independent and use bundled standard libraries. SQL checks are structural and do not connect to a database. PHP uses a browser parser with 7.4 and 8.3 presets, not the native php -l command. Vue and Svelte checks include recognized script and style blocks, with problem locations mapped back into the original file.

Review changes before applying them

For languages with supported fixes or formatting, inspect the original and proposed source in the preview first. Applying the preview makes one undoable edit. A preview becomes stale when the source or checking settings change, so an earlier result cannot silently rewrite newer work. Formatting is available only when a formatter is bundled for that mode, and Python fixes are reviewed individually. Syntax errors still require judgment: the following missing expression could have many possible intended values.

// JavaScript: missing right-hand expression
const total = ;

// JavaScript: valid assignment
const total = 42;

Keep source and reports under your control

Analysis runs in background browser workers without executing submitted code. Engine scripts and grammars load from this site, while your source, filenames and diagnostics stay in the workspace. No source is silently persisted. Choose Save workspace to store it in IndexedDB on this browser, or export a workspace JSON file when you want a portable copy. Exported workspaces and problem reports can contain private information, so share those files deliberately. Removing browser site data also removes local saves.

Use the studio alongside your development workflow

Use this workspace to investigate copied snippets, review a generated configuration, compare syntax between language versions or prepare a concise issue report. The editor includes line numbers, folding, bracket matching, search and replace, wrapping and indentation settings. Resource limits keep large or malformed inputs from blocking the interface: each workspace accepts up to 20 files, at most 1 MiB each and 5 MiB combined. Timed-out and failed checks remain visibly different from a successful check and can be retried. Continue to run your normal compiler, runtime checks and project tests before publishing a change.

Compare the edited code with Code Diff · Compare structured data with JSON Diff