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Local-first tools for developers
DevKnightUtils

Local-first tools for developers who need useful pages, not thin utility shells.

DevKnightUtils combines interactive utilities with practical explanations, real use cases, FAQs, privacy notes and internal linking so each route is useful before and after you click the main tool.

How we build tools

Why this site is different

  • Every tool page should explain the problem, not only show a textarea.
  • Privacy notes are surfaced where developers actually paste data.
  • Related tools keep multi-step debugging workflows in one place.

Privacy-first by default

Many utilities on this site are designed to process data locally in the browser. That matters when you are inspecting auth tokens, production payloads, API specs or config fragments.

Featured workflows

These are some of the routes most likely to solve real debugging, formatting and documentation tasks quickly.

JSON Formatter / Beautifier

Data & Text

Format, validate, and minify JSON data.
Open tool
JWT Decoder

Security

Decode JSON Web Tokens and view their header, payload, and signature.
Open tool
OpenAPI Validator

Data & Text

Validate OpenAPI / Swagger 2.0 and 3.0 specifications (JSON or YAML).
Open tool
Base64 Codec

Data & Text

Encode and decode Base64 strings instantly.
Open tool
Regex Tester

Data & Text

Test and debug regular expressions in real-time right in your browser.
Open tool
Image Converter & Optimizer

Media

Compress and convert images (JPEG, PNG, WebP) entirely in your browser.
Open tool

Security and auth

JWT inspection, key generation, password analysis and hashing utilities for everyday auth and security workflows.

Formats and validators

JSON, XML, YAML, CSV, SQL and OpenAPI tools built to shorten debugging and reduce copy-paste friction.

Converters and docs

Base64, URL encoding, Markdown, HTML and data conversion tools for moving between formats safely.

Why developers use DevKnightUtils

  • Fast utilities for tasks that otherwise interrupt implementation flow.
  • Editorial context so the route is still useful to humans and crawlers.
  • Privacy messaging where it matters: on pages that handle potentially sensitive input.
  • Straightforward linking between adjacent tasks like format, validate, compare and convert.

Useful site pages

AboutContactGeneral FAQSecurity & privacyHow we build toolsChangelog

General FAQ

Are these just simple wrappers around third-party APIs?

No. The goal is to make each route useful on its own with tool UI, context, examples and local-first handling where possible.

Do I need an account?

No. The core utility routes are designed to be immediately usable without sign-up friction.

Will more guides and tutorials be added?

Yes. The site is moving from a pure utility collection toward a richer knowledge layer around those workflows.

How do I report a bug or suggest a tool?

Use the contact page. That route exists so the site has a visible owner, a feedback path and a support surface.

All developer tools

Browse the full library. Each route should expose a real use case, not just a repeated UI shell.

JWT Decoder
Security
Decode JSON Web Tokens and view their header, payload, and signature.
JWT Generator
Security
Create HS256/HS384/HS512 signed JWT tokens for API testing.
SQL → C# Entity Generator
Data & Text
Convert SQL CREATE TABLE statements into C# classes for Entity Framework Core.
OpenAPI Validator
Data & Text
Validate OpenAPI / Swagger 2.0 and 3.0 specifications (JSON or YAML).
Mermaid Editor
Data & Text
Create and preview text-based Mermaid.js diagrams in real time.
Visual Whiteboard
Data & Text
Interactive drag-and-drop whiteboard to draw diagrams, architectures, and wireframes.
Base64 Codec
Data & Text
Encode and decode Base64 strings instantly.
URL Encoder / Decoder
Data & Text
Encode and decode URLs and query strings with percent-encoding (RFC 3986).
Regex Tester
Data & Text
Test and debug regular expressions in real-time right in your browser.
Diff Checker — Text & JSON
Data & Text
Compare two text blocks or JSON and highlight line-by-line differences.
JSON Formatter / Beautifier
Data & Text
Format, validate, and minify JSON data.
Hash Generator
Security
Calculate MD5, SHA-1, SHA-256, and SHA-512 hashes instantly.
Image Converter & Optimizer
Media
Compress and convert images (JPEG, PNG, WebP) entirely in your browser.
PDF Metadata Editor
Media
Inspect and modify PDF metadata properties safely.
Data Format Converter
Data & Text
Convert structure data instantly between JSON, XML, YAML and Markdown.
XML Formatter / Beautifier
Data & Text
Format, validate, and minify XML data.
YAML Formatter
Data & Text
Format, validate, and align YAML configuration files.
HTML → Markdown Converter
Data & Text
Convert HTML markup to clean Markdown syntax, locally in your browser.
Markdown Table Generator
Data & Text
Build complex Markdown tables visually with an interactive grid editor.
Markdown Previewer
Data & Text
Real-time GitHub-style Markdown editor and preview, 100% in your browser.
JSON ↔ CSV Converter
Data & Text
Bidirectional conversion between JSON arrays and CSV format, locally in your browser.
SQL Formatter & Beautifier
Data & Text
Format and beautify SQL queries with keyword highlighting, locally in your browser.
CSV Validator
Data & Text
Verify CSV structure: column consistency, quoting, and delimiter detection.
Cron Job Descriptor
DevOps
Translate cron expressions into plain human language in 6 languages.
.env Masker & Validator
DevOps
Parse .env files, mask sensitive values, validate key syntax, and export safe templates.
UUID / ULID Generator
DevOps
Generate bulk UUID v4 and ULID unique identifiers instantly in your browser.
Password Entropy Analyzer
Security
Analyze password strength in bits of entropy and estimate crack time.
RSA Key Pair Generator
Security
Generate RSA public/private key pairs (2048/4096-bit) using the Web Crypto API.
Htpasswd Generator
Security
Generate .htpasswd files with bcrypt or SHA-1 hashes for Apache/Nginx basic auth.

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