44 tools DEV

Free Developer Tools

An everyday toolbox for modern engineers: decode JWTs, test and explain regexes, count AI prompt tokens, inspect stack traces and source maps, and generate strongly-typed code from JSON for TypeScript, Go, Dart, Rust, C#, Pydantic, Zod, and more. Every tool runs client-side — your code never touches a server.

Runs in browserNo signup requiredAI-enhanced

44 tools in this category

View all tools
LocalAI

JWT Decoder

Decode, inspect, and validate JWT tokens with claim and signature analysis.

jwtdecodeDEV
LocalAI

Cron Parser

Parse, validate, explain, and build cron expressions with next run times and visual timeline.

croncrontabDEV
LocalAI

Regex Tester

Test, debug, and explain regular expressions with real-time match highlighting.

regexregexpDEV
Local

Regex Explainer

Break down any regex into plain English, token by token.

regexregexpDEV
LocalAI

JSON to TypeScript & Schema Generator

Generate TypeScript interfaces, Zod schemas, and Valibot schemas from JSON.

jsontypescriptDEV
Local

AI Token Counter

Count tokens and estimate API costs for 100+ LLMs with exact BPE and provider tokenization.

tokensaiDEV
LocalAI

AI Prompt Builder

Build structured LLM prompts with per-section token counting, variable injection, and provider-aware exports for OpenAI, Anthropic, and Google.

aipromptDEV
Local

Number Base Converter

Convert numbers between binary, octal, decimal, hexadecimal and custom bases.

binaryoctalDEV
LocalAI

JSON Path Tester

Query and extract data from JSON documents using JSONPath.

jsonjsonpathDEV
Local

Env File Parser & Converter

Parse, validate, and convert .env files between JSON, YAML, Docker, and Kubernetes formats.

envdotenvDEV
LocalAI

Stack Trace Analyzer

Parse, format, and analyze error stack traces with root cause isolation.

stack-traceerrorDEV
LocalAI

Tech Stack Detector

Detect frameworks, CMS platforms, analytics, and server technologies used by any website.

tech-stackdetectorDEV
LocalAI

Source Map Explorer

Resolve minified stack traces back to original source code using source maps.

source-mapminifiedDEV
AI

GraphQL Query Builder

Build and test GraphQL queries with schema introspection and AI suggestions.

graphqlapiDEV
LocalAI

Prompt Injection & Secret Scanner

Scan prompts, code, and text for prompt injection patterns, secret leaks, unsafe instructions, and PII exposure.

aipromptDEV
LocalAI

MCP Schema Validator

Validate, format, test, and debug Model Context Protocol (MCP) server schemas and tool definitions.

mcpmodel context protocolDEV
Local

JSON to Dart

Convert JSON to null-safe Dart classes with json_serializable & fromJson constructors.

jsondartDEV
Local

JSON to Go Struct

Convert JSON to Go structs with json tags and idiomatic naming.

jsongoDEV
Local

JSON to TypeScript

Convert JSON to TypeScript interfaces or type aliases instantly.

jsontypescriptDEV
Local

JSON to Zod Schema

Convert JSON to Zod schema definitions with automatic TypeScript type inference.

jsonzodDEV
Local

JSON to Rust Struct

Convert JSON into idiomatic Rust structs with Serde Serialize and Deserialize derive macros.

jsonrustDEV
Local

JSON to C# Class

Convert JSON to C# classes with System.Text.Json or Newtonsoft serialization.

jsoncsharpDEV
Local

JSON to Pydantic Model

Convert JSON and JSON Schema into typed Pydantic v2 and v1 BaseModel classes for FastAPI, Django Ninja, and Python applications.

jsonpythonDEV
Local

JSON to SQL Converter

Convert JSON arrays to SQL CREATE TABLE and INSERT statements.

jsonsqlDEV
Local

JSON to Protobuf Schema Generator

Generate Protocol Buffer (.proto) schema definitions from JSON objects.

jsonprotobufDEV

OpenAPI to Postman Collection Converter

Convert OpenAPI/Swagger specs to Postman Collection v2.1 JSON.

openapiswaggerDEV

OpenAPI to TypeScript Converter

Convert OpenAPI/Swagger specs (JSON or YAML) to TypeScript interfaces, types, or Zod schemas.

openapiswaggerDEV

Postman to OpenAPI Converter

Convert Postman Collection v2.1 JSON to OpenAPI 3.0.0 specification.

postmanopenapiDEV
Local

GraphQL Schema to TypeScript Generator

Generate TypeScript types from GraphQL SDL schema definitions.

graphqltypescriptDEV
Local

JSON to .env Converter

Convert JSON configuration objects to .env files, Docker env, or Kubernetes ConfigMaps.

jsonenvDEV
Local

Docker Compose to Kubernetes

Convert docker-compose.yml to Kubernetes Deployment, Service, ConfigMap, and PVC manifests.

dockerkubernetesDEV
Local

Protobuf Inspector

Parse and inspect Protocol Buffer .proto files — view message structures, field types, enums, and services.

protobufprotoDEV
Local

JSON to Parquet Converter

Convert JSON arrays to Apache Parquet columnar format using DuckDB WASM, right in your browser.

jsonparquetDEV
LocalAI

Kubernetes YAML Validator

Validate, lint, and format Kubernetes manifests against structure rules, deprecated APIs, and security best practices.

kubernetesk8sDEV
Local

LLM JSON Schema Generator

Generate JSON Schema for LLM structured outputs — OpenAI, Anthropic, Gemini, Ollama.

json-schemallmDEV
Local

AI Cost Calculator

Model and compare LLM API spend across 120+ providers for any workload with prompt caching and batch pricing.

aillmDEV
LocalAI

Dockerfile Linter

Lint, validate, format, and optimize Dockerfiles with Hadolint-compatible rules, security checks, and multi-stage analysis.

dockerfiledockerDEV
LocalAI

JSON Schema Visualizer & Tree Explorer

Render Draft-07 / 2020-12 JSON Schemas into interactive visual trees, documentation diagrams, and realistic mock data.

json-schemavisualizerDEV
Local

SQLite Viewer

Open and query SQLite databases, CSV, and JSON files with full SQL — 100% private in your browser.

sqlitesqlDEV
Local

LLM Tool & Function Schema Converter

Convert tool and function calling definitions between OpenAI, Anthropic, Gemini, MCP, Vercel AI SDK, TypeScript, and Pydantic.

llmopenaiDEV
Local

OpenTelemetry Trace Waterfall Visualizer

Visualize and analyze OpenTelemetry (OTel), Jaeger, and Zipkin traces with an interactive Gantt waterfall, critical path, and latency breakdown.

opentelemetryotelDEV
Local

Nginx Config Validator

Validate Nginx configuration syntax, reverse proxy rules, and SSL security

nginxlinterDEV
Local

Systemd Unit Generator

Generate production-ready, hardened systemd service unit files with CLI commands

systemdlinuxDEV
Local

OpenAPI to Pydantic

Convert OpenAPI 3 & Swagger specs (YAML/JSON) to Python Pydantic models

openapiswaggerDEV

Developer Tools Guides & Technical Standards

Master workflows, understand protocol specifications, and avoid production edge-cases.

Technical Field Manuals

.env File Formatting & Escaping: Multiline Secrets, Quotes & 12-Factor Config

Master .env formatting rules, resolve multiline string and certificate escaping bugs, manage .env precedence, and prevent secret leaks in CI/CD.

Automating API Contract Testing: Converting OpenAPI 3.1 to Postman Collections

Transform OpenAPI (Swagger) specifications into executable Postman Collections (v2.1). Automate contract testing, generate mock servers, and streamline API integration.

Clean HTML to Markdown for LLM & RAG Pipelines: Token Minimization & Semantic Table Extraction

Strip DOM boilerplate, convert complex HTML tables and semantic trees into clean Markdown, slash RAG embedding token costs by 60–80%, and preserve critical context for LLMs.

Converting cURL Commands to Clean Node.js, Python, and Go HTTP Clients

Transform raw cURL commands and browser network exports into production-ready JavaScript Fetch, Axios, Python Requests/HTTPX, and Go net/http code.

Converting JSON to Apache Parquet: Optimizing Analytics & Storage Costs

Learn how to convert nested JSON datasets to columnar Apache Parquet with schema inference, Snappy/ZSTD compression, and DuckDB/Athena query acceleration.

Cryptographic Hash Functions in Modern Web Architecture: SHA-2, SHA-3, BLAKE2 & HMAC Guide

Master cryptographic hashing: evaluate collision resistance, benchmark SHA-2 vs SHA-3 vs BLAKE2, prevent length extension attacks with HMAC, and safely verify file checksums.

De-minifying Production Stack Traces: Source Map Resolution Guide

Resolve minified JavaScript bundle errors back to original TypeScript source code using VLQ-decoded source maps, hidden source maps, and stack trace resolvers.

Debugging JWT Errors: Fixing Signature Verification, Expiration & JWKS Failures

A comprehensive developer debugging guide to resolving JSON Web Token (JWT) errors: signature mismatches, expired tokens, alg: none attacks, clock skew, and JWKS key rotation.

Detecting Website Technology Stacks: Frameworks, CMS & Server Fingerprinting Guide

Learn how to detect frontend frameworks, CMS platforms, CDN edge layers, and server runtimes using DOM markers, script paths, and HTTP response headers.

Dockerfile Best Practices: Layer Caching, Multi-Stage Builds & Security Hardening

A comprehensive developer guide to writing production-grade Dockerfiles: mastering BuildKit cache invalidation, multi-stage builds, non-root execution, and security linting.

Frontend Bundle Size Optimization: Tree-Shaking, Chunk Splitting & Dead Code Elimination

Diagnose JavaScript bundle bloat, fix broken tree-shaking patterns, eliminate barrel file overhead, and optimize Core Web Vitals (INP/LCP) in Next.js, Vite, and Webpack.

Generating Python Pydantic V2 Models from JSON: Schemas, Field Validators & Nested Types

Convert raw JSON payloads and schemas into robust, type-safe Python Pydantic V2 models. Master Field constraints, custom validation, and nested structures.

Generating Realistic Mock Data for APIs: MSW, Faker, and JSON Schemas

Master synthetic mock data generation for APIs: build realistic datasets using Faker, JSON Schema, and Mock Service Worker (MSW 2.0) for frontend testing and prototyping.

Generating TypeScript Types from JSON: Schemas, Interfaces & Zod

How to generate type-safe TypeScript interfaces, Zod runtime validation schemas, and JSON Schema definitions from arbitrary JSON payloads.

GitHub Actions YAML Workflow Debugging: The Top 10 Syntax & Runtime Pitfalls

A comprehensive developer guide to identifying and fixing GitHub Actions YAML syntax errors, matrix build bugs, expression interpolation traps, and concurrency race conditions.

GraphQL Schema to TypeScript: Automated Type Generation, Operations & Codegen Guide

Generate end-to-end type safety across your GraphQL stack. Learn how to convert GraphQL SDL schemas and documents into typed queries, mutations, and resolver signatures.

Handling HTTP 429 Too Many Requests: Rate Limiting Headers, Exponential Backoff & Jitter

Diagnose and handle HTTP 429 status codes. Master IETF standard RateLimit and Retry-After headers, and implement production-grade exponential backoff with full jitter in Node.js, Python, and Go.

How to Read, Deconstruct, and Understand Complex Regular Expressions

Master the art of reading cryptic regular expressions by breaking patterns down into visual abstract syntax trees, grouping constructs, lookarounds, and quantifiers.

ISO 8601, Unix Timestamps & Timezones: Zero-Discrepancy Time in Distributed Systems

Master epoch timestamps, millisecond vs microsecond precision, RFC 3339 / ISO 8601 formatting, UTC storage rules, and prevent subtle timezone bugs across databases and APIs.

JSON Formatting & Validation Best Practices: Production Guide

Master JSON formatting, RFC 8259 compliance, JSON Schema Draft 2020-12 validation, safe 64-bit integer handling, and high-throughput Node.js streaming.

JSONL vs JSON: Streaming Large Datasets, LLM Fine-Tuning & NDJSON Best Practices

Understand the differences between JSON and JSON Lines (JSONL / NDJSON). Learn how to stream massive datasets, format AI training data, and process lines in Python and Node.js.

JSONPath Syntax Cheat Sheet: Querying, Filtering & RFC 9535 Expressions

Master standard JSONPath syntax, filter expressions, recursive descent, and array slicing for REST APIs, mock tests, and log filtering.

Kubernetes YAML Validation: The 10 Most Common Manifest Mistakes

Diagnose and fix syntax errors, missing resource limits, selector mismatches, and schema validation failures in Kubernetes manifests before deployment.

LLM API Cost Optimization: Prompt Caching, Model Routing & Token ROI

Slash your OpenAI, Anthropic, and Gemini API bills by 60–80%. Master prompt caching, tiered model routing, token budgeting, and batch processing economics.

LLM Token Counting & Context Window Budgeting: BPE Tokenizers & Cost Optimization

Understand BPE tokenization, calculate prompt vs output token consumption, utilize prompt caching, and budget context windows to optimize AI inference costs.

Mastering Cron Expressions: Syntax, Timezones, and DST Gotchas

Master 5-field and 6-field cron syntax, prevent double executions during Daylight Saving Time (DST), handle UTC schedules, and debug missed server jobs.

Mastering CSS Selectors: Specificity Math, Relational :has(), and Modern Pseudo-Classes

A comprehensive developer guide to CSS selectors, specificity calculation mechanics, the :has() relational selector, forgiving selector lists, and high-performance DOM querying.

Mastering Git Merge Conflict Resolution: 3-Way Diff, Diff3 Markers & Rebase Workflows

Resolve Git merge and rebase conflicts with confidence. Master standard vs diff3 conflict markers, 3-way merge logic, and conflict prevention strategies.

Mastering JSON to C# Class Serialization: System.Text.Json, Records & .NET Best Practices

Learn how to convert JSON payloads into robust, idiomatic C# classes and records. Master System.Text.Json, JsonPropertyName, Newtonsoft.Json, nullable reference types, and custom converters.

Mastering JSON to Dart & Flutter Serialization: Null Safety, json_serializable & Freezed

Learn how to convert JSON payloads into robust, null-safe Dart models for Flutter. Master manual factory constructors, json_serializable, build_runner, and Freezed.

Mastering JSON to Go Struct Serialization: encoding/json, Struct Tags & Custom Unmarshaling

Learn how to convert JSON payloads into robust, idiomatic Go structs. Master struct tags, omitempty edge cases, pointer nullability, and custom unmarshaling.

Mastering JSON to Rust Struct Serialization: Serde, Derives & Zero-Copy Parsing

Learn how to convert JSON payloads into robust, idiomatic Rust structs with Serde. Master derive macros, Option<T> nullability, rename_all, and zero-copy deserialization.

Mastering LLM Structured Outputs: Enforcing JSON Schema in Production

Master structured outputs with LLMs using JSON Schema Draft 2020-12, OpenAI strict schemas, Anthropic tool definitions, and token-optimized validation pipelines.

Mastering Number Base Conversions: Binary, Hex, Two's Complement & IEEE 754 Floating Point

A comprehensive developer guide to positional numeral systems, arbitrary-precision BigInt radix conversions, two's complement signed arithmetic, and IEEE 754 float inspection.

Mastering Responsive Web Design: Viewports, CSS Breakpoints & Multi-Device Testing

A comprehensive developer guide to responsive web design, covering layout vs visual viewports, modern CSS media queries, container queries, fluid typography, and viewport testing strategies.

Mastering SQL Execution Plans: Reading EXPLAIN ANALYZE, Index Scans & Query Optimization

Diagnose slow database queries by decoding EXPLAIN (ANALYZE, BUFFERS) output trees, optimizing composite indexes, understanding bitmap heap scans, and eliminating sequential scans.

Migrating from Docker Compose to Kubernetes: Complete Translation Guide

Translate Docker Compose stacks into production-ready Kubernetes manifests. Map services to Deployments, host volumes to PVCs, and env files to ConfigMaps.

Model Context Protocol (MCP) Server Schema Validation & Tool-Calling Debugging

A technical guide to authoring, validating, and debugging JSON Schema tool definitions for Model Context Protocol (MCP) servers in AI agents and LLM applications.

Modern Cookie Security & CSRF Prevention: SameSite, __Host- Prefixes & CHIPS

Implement bulletproof browser cookie security with SameSite=Lax/Strict, enforce host binding via __Host- and __Secure- prefixes, prevent CSRF attacks, and configure CHIPS for cross-site embeds.

Modern CSS Color Spaces: Mastering OKLCH, Display P3, Hex & HSL Conversions

A comprehensive developer guide to modern web color spaces: understanding OKLCH perceptual uniformity, Display P3 wide gamut, sRGB conversions, and accessible UI palettes.

Modern Password Hashing in 2026: Argon2id vs bcrypt vs PBKDF2 & OWASP Security Standards

Benchmark memory-hard Argon2id against bcrypt and PBKDF2, configure work factors for modern GPU resistance, avoid the 72-byte bcrypt truncation trap, and implement seamless on-login hash upgrades.

OpenAPI to TypeScript: Automated Type Generation, REST Contracts & Zod Guide

Generate end-to-end type safety from OpenAPI and Swagger specs. Learn how to convert OAS 3.0/3.1 JSON/YAML schemas into typed fetch clients, Zod validators, and path types.

Prompt Injection Scanning: A Practical Security Checklist

A developer security guide to identifying direct, indirect, and multi-turn prompt injection vulnerabilities in LLM applications and agent pipelines.

Protobuf Debugging: Reading Wire-Format Errors & Binary Streams

A developer guide to Protocol Buffers wire format, decoding varints, resolving tag mismatches, and debugging corrupt binary gRPC and Kafka streams.

Regex Catastrophic Backtracking: How to Detect, Debug, and Prevent ReDoS

Understand NFA regular expression engine backtracking, diagnose exponential runtime traps, and fix Regular Expression Denial of Service (ReDoS) vulnerabilities.

Repairing Malformed & AI-Generated JSON: Field Guide to Syntax Recovery

Learn how to repair broken JSON from LLM outputs, APIs, and configs. Master automated AST recovery for trailing commas, single quotes, bare keys, and truncated streams.

Runtime Schema Validation: Converting JSON to Zod for Type-Safe TypeScript APIs

Bridge the gap between compile-time TypeScript interfaces and runtime boundary validation. Learn how to generate, refine, and enforce Zod schemas from JSON payloads.

Server-Sent Events (SSE) vs WebSockets: Streaming Architecture for LLM & Real-Time APIs

Master unidirectional SSE vs bidirectional WebSockets for modern applications. Learn HTTP/2 multiplexing, automatic reconnection, Nginx proxy buffering gotchas, and token-by-token LLM streaming.

Subnetting & CIDR Calculations: A Practical Cheat Sheet for Developers

Master IPv4/IPv6 CIDR notation, subnet mask bitwise math, usable IP ranges, broadcast addresses, and cloud VPC network design for AWS, Docker, and Kubernetes.

TOML Configuration Syntax, Arrays of Tables & Parsing: The Complete Developer Guide

Master TOML v1.0.0 configuration grammar, understand arrays of tables vs inline tables, parse Cargo.toml and pyproject.toml manifests, and serialize TOML across runtimes.

Visual Text Diffing, Unified Diff Syntax & Git Patch Workflows

Master code diff algorithms (Myers, Patience, Histogram), unified diff patch anatomy (@@ coordinates), side-by-side vs inline comparison, and patch workflows.

Visualizing and Debugging Complex JSON Schemas: $defs, Recursion, and OpenAPI 3.1

Master JSON Schema visualization and debugging: resolve complex $defs pointers, catch recursive circular loops, inspect validation constraints, and render OpenAPI diagrams.

RFC Standards & Terminology

AI Tokens (LLM Tokenization & Context Windows)AI & Machine LearningAPI Rate Limiting Algorithms & HTTP 429 HeadersNetworkBase64 EncodingEncodingByte-Pair Encoding (BPE Tokenization in LLMs)AI & Machine LearningC# Classes, Records & JSON Serialization in .NETDeveloper ToolscamelCase & Identifier Naming ConventionsText ProcessingColor Spaces & Models (RGB, HSL, OKLCH, Hex)Web StandardsCron Expressions & Crontab SyntaxDevOpsDart Programming LanguageProgramming LanguagesDocker Compose & Multi-Container OrchestrationDevOpsDockerfile (Container Image Build Specification)DevOpsDotenv (.env Configuration Files)Configuration & DevOpsGitHub Actions (CI/CD & Workflow Automation)DevOpsGo Structs & JSON Serialization in GolangDeveloper ToolsGraphQL (Query Language for APIs)Web DevelopmentgRPC High-Performance Remote Procedure Call FrameworkNetworkHTTP Headers (Request & Response Metadata)NetworkingIANA Time Zone Database (tzdb), Olson IDs & UTC OffsetsDateTimeISO 8601 & RFC 3339 Date-Time StandardDateTimeJSON (JavaScript Object Notation)Data FormatsJSON Patch (RFC 6902) Document UpdatesText & DataJSON Schema (Draft 2020-12)Data FormatsJSONPath Expression Syntax & QueryingText & DataJSON Web Token (JWT)SecurityJWT Registered & Private Claims (RFC 7519)SecurityModel Context Protocol (MCP)AI & Machine LearningNDJSON (Newline Delimited JSON)Data FormatsOAuth 2.0 Authorization FrameworkSecurityOpen Container Initiative (OCI) SpecificationsDeveloper ToolsOpenAPI Specification (formerly Swagger)API StandardsOpenTelemetry (OTel) Observability FrameworkDeveloper ToolsPasskeys Cryptographic Passwordless AuthenticationSecurityProof Key for Code Exchange (PKCE)SecurityPrompt Caching (LLM Context Caching & KV Cache)AI & Machine LearningPrompt Engineering (Techniques & Best Practices)AI & Machine LearningPrompt Injection (OWASP LLM01 Attacks & Guardrails)AI & Machine LearningProtocol Buffers (Protobuf)Data FormatsPydantic Data Validation & Settings Management Library for PythonDeveloper ToolsRegular Expression (Regex)Text ProcessingSoftware Bill of Materials (SBOM)Developer ToolsSerde Serialization & Deserialization Framework for RustDeveloper ToolsJavaScript Source Maps (V3 Specification)Developer ToolsSQL (Structured Query Language)DatabaseStack Trace (Error Call Stack & Traceback)Developer ToolsTech Stack (Web Technology Fingerprinting & Architecture)ArchitectureTOML (Tom's Obvious Minimal Language)Data FormatsTree Shaking & Dead Code Elimination in JavaScript BundlersDeveloper ToolsTwo's Complement Binary RepresentationComputer ScienceTypeScript Programming Language & Type SystemProgramming LanguagesUnix Timestamp (Epoch Time) & POSIX TimeDateTimeWeb Authentication API (WebAuthn / FIDO2)SecurityYAML (YAML Ain't Markup Language)Data FormatsZod Schema Declaration & Runtime Validation LibraryDeveloper Tools

Browse other categories

Frequently Asked Questions

Are the developer tools free?+

Yes, all 34 developer tools are free with no usage limits. JWT decoding, regex testing, JSON-to-code generation, and everything else runs directly in your browser.

Can these tools generate code from JSON?+

Yes. The codegen tools accept a JSON document and output typed definitions for TypeScript interfaces, Go structs, Dart classes, Rust structs, C# classes, Pydantic models, Zod schemas, SQL schemas, and more.

Does the JWT decoder send my token anywhere?+

No. The JWT decoder parses the token locally in your browser and shows the raw decoded header and payload. Nothing is transmitted, stored, or logged.

Do I need an account to use these developer tools?+

No account or signup is required. Tools work instantly on paste for quick regex testing, JWT inspection, and code generation.