Guides, tips and best practices for working with JSON.
Special characters in JSON strings — quotes, backslashes, newlines — must be escaped or they break parsing. The full guide explains all 9 escape sequences defined in RFC 8259, the most common mistakes (raw newlines, unescaped double quotes, double-escaped backslashes), and complete implementations for escaping and unescaping in JavaScript, Python, Go, and PHP.
SyntaxError: Unexpected token is the most common JSON error. Every cause is explained with before/after examples — trailing commas, single quotes, comments, undefined values, BOM characters, and more.
Stop writing TypeScript interfaces by hand. Paste any JSON and get properly typed interfaces instantly — including nested objects, optional fields, arrays, and null union types.
Master JSON Schema validation — types, required properties, string patterns, array constraints, $ref references, if/then/else conditionals, and real code examples in JavaScript (Ajv) and Python.
Production-tested JSON API design principles: naming conventions, date handling, null vs missing fields, pagination patterns, RFC 7807 error format, versioning, and performance tips used by real APIs.
Modern JavaScript provides powerful tools for working with JSON — destructuring for clean property access, optional chaining to prevent "cannot read property of undefined" errors, fetch API with async/await for typed responses, structuredClone() for deep copying, and Web Workers for parsing large JSON without blocking the UI.
Read Full Guide →Large JSON payloads slow down APIs and hurt Core Web Vitals. This guide covers HTTP compression (gzip, Brotli) with nginx and Node.js config, JSON minification, field pruning, key shortening, NDJSON streaming for progressive rendering, JSON Patch for delta updates, and when to switch to MessagePack or CBOR.
Read Full Guide →JSON to CSV conversion involves flattening nested objects and mapping array items to rows — but edge cases abound. This guide covers the full algorithm, handling nested objects with dot notation, arrays with multiple strategies, missing fields, large files via streaming, and complete working implementations in JavaScript, Python, and command-line tools.
Learn JSON from scratch with 7 hands-on lessons — live sandbox, fix-the-bug exercises, quizzes, and a printable cheat sheet. No signup, no setup required. Covers JSON syntax, data types, nesting, arrays, and common mistakes with immediate feedback.
Start the Interactive Tutorial →Six battle-tested methods to validate JSON — online validator, command line (Python, jq, Node.js), and code in JavaScript, Python, and Go. Covers the 10 most common syntax errors with before/after fixes, plus JSON Schema validation for enforcing data structure beyond syntax.
Read Full Guide →A complete guide to JSON Web Tokens — header, payload, and signature structure; creating and verifying JWTs in Node.js and Python; common security vulnerabilities (alg:none attack, weak secrets, missing expiry); and best practices for production use. Includes a live decoder tool.
Read Full Guide →JSON.parse() and JSON.stringify() block the JavaScript main thread. This guide covers Web Workers for offloading large parses, NDJSON streaming for incremental rendering, structuredClone() as a faster deep-clone alternative, and when to switch to MessagePack or binary formats for performance-critical paths.
Read Full Guide →JSON carries serious security risks that are easy to miss — prototype pollution via Object.assign(), the JWT alg:none exploit that bypasses signature verification, PII exposure in log files, and injection through unsanitized JSON embedded in HTML. This guide explains each attack and how to defend against it with concrete code examples.
Read Full Guide →JSONPath lets you query nested JSON with XPath-style expressions. This tutorial covers the full JSONPath syntax — recursive descent, wildcards, array slices, filter expressions, and script expressions — with examples for every operator and a live query tool to test your expressions instantly.
Read Full Tutorial →JSON and XML serve different use cases. This guide compares them on verbosity, data types, schema support, streaming, and ecosystem tooling — with a side-by-side example of the same data in both formats. Includes a decision framework for choosing the right format for your API, config files, or data pipelines.
Read Full Guide →YAML is a superset of JSON that adds comments, multiline strings, anchors, and human-friendly syntax — but also more complexity and subtle parsing pitfalls. This guide explains when to prefer YAML (CI/CD configs, Kubernetes, Ansible) vs JSON (APIs, browser storage, data interchange), with conversion examples.
Read Full Guide →JSON syntax validation only checks if JSON is well-formed. JSON Schema validation checks if the data is correct — right types, required fields, value ranges, string patterns, and array constraints. This tutorial walks through writing your first schema, understanding draft versions, and integrating validation into a TypeScript project with Ajv.
Read Full Tutorial →Build JSON APIs that are consistent, backward-compatible, and developer-friendly. This guide covers camelCase naming conventions, RFC 7807 problem details for error responses, cursor vs offset pagination for large datasets, URL vs header-based API versioning, and security practices to prevent mass assignment and field exposure.
Read Full Guide →JSON.stringify() and JSON.parse() are the foundation of JSON handling in JavaScript, but both have non-obvious behaviors — the replacer and reviver functions, handling of undefined/NaN/Infinity, circular reference errors, deep-clone limitations, and the space parameter for pretty-printing. This guide covers all of them with practical examples.
Read Full Guide →Comprehensive JSON interview preparation covering basic syntax, data type handling, JSON Schema, JWT security, JSONPath queries, and performance optimization. Questions progress from beginner (what are the six JSON types?) through intermediate (difference between JSON and JSONB in PostgreSQL) to advanced (prototype pollution attacks). Perfect for frontend, backend, and full-stack roles.
See All 50 Questions →Store and query JSON efficiently across relational and document databases. Covers PostgreSQL JSONB operators and GIN index setup for fast containment queries, MySQL JSON type with generated column indexing, MongoDB BSON types and $jsonSchema document validation, and a decision guide for when to use JSON columns vs normalized relational tables.
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