Free Online Utility Tools
MojoUtils — 55+ tools for developers, designers, and everyone.
AI Tools (25)
AI Skill Generator
Generate structured SKILL.md files for reusable AI workflows
AGENTS.md Generator
Create agent instruction files for Codex, Claude Code, and Gemini CLI
System Prompt Builder
Build clear system prompts with role, rules, output format, and examples
Prompt Optimizer
Rewrite rough prompts into structured, higher-signal prompts
Markdown Instruction File Generator
Generate README, AGENTS, CLAUDE, GEMINI, and contribution markdown files
AI Output Format Generator
Create JSON, Markdown, YAML, CSV, and checklist output specifications
Agent Task Prompt Generator
Generate task prompts for Codex, Claude Code, and Gemini CLI coding agents
AI Code Review Checklist Generator
Create focused code review checklists for AI and human reviewers
Prompt Diff Checker
Compare two prompts and summarize instruction changes
AI Persona Generator
Create reusable assistant personas with tone, boundaries, and response rules
AI Image Prompt Builder
Build image prompts with subject, style, composition, lighting, and negative prompts
AI Video Prompt Builder
Create video prompts with scene, action, camera movement, duration, and motion style
Shot List Generator
Generate shot lists for AI videos, reels, ads, and product demos
Storyboard Prompt Generator
Create scene-by-scene storyboard prompts with style and character consistency
Negative Prompt Generator
Generate negative prompts for portraits, products, architecture, logos, anime, and video
Aspect Ratio & Resolution Calculator
Calculate aspect ratios, platform resolutions, and crop-safe guidance
Style Reference Prompt Generator
Describe visual styles without relying on artist names or copyrighted references
Character Consistency Sheet Generator
Create character bibles for consistent AI image and video generation
Product Photo Prompt Generator
Generate product photography prompts for white background, lifestyle, hero, and detail shots
Logo Prompt Generator
Create AI logo, icon, and wordmark prompt directions with practical limitations
Ad Creative Prompt Generator
Generate prompts for static ads, video ads, hooks, thumbnails, and CTA variants
Thumbnail Prompt Generator
Create thumbnail prompts with subject, emotion, safe text area, and contrast direction
Prompt Token & Length Estimator
Estimate prompt length and identify overly long image or video prompts
Prompt Variant Generator
Create multiple creative prompt variants from one base idea
AI Creative Brief Generator
Generate creative briefs with image prompts, video prompts, deliverables, and review checklists
Unit Converters (7)
Length Converter
Convert between mm, cm, m, km, inch, ft, yard, mile
Weight Converter
Convert between mg, g, kg, ton, oz, lb
Temperature Converter
Convert between Celsius, Fahrenheit, and Kelvin
Data Size Converter
Convert between Bit, Byte, KB, MB, GB, TB, PB
Area Converter
Convert between mm², cm², m², km², acre, and hectare
Volume Converter
Convert between mL, L, m³, gallon, quart, pint, and more
Speed Converter
Convert between m/s, km/h, mph, knot, and ft/s
Developer Tools (9)
JSON Formatter & Validator
Format, validate and minify JSON data
URL Encoder / Decoder
Encode or decode URL strings
Base64 Encoder / Decoder
Encode or decode Base64 strings
UUID Generator
Generate random UUID v4 strings
HTML Entity Encoder / Decoder
Encode or decode HTML entities like < > &
CSS Minifier
Minify CSS by removing whitespace and comments
JS Minifier
Minify JavaScript by removing whitespace and comments
JWT Decoder
Decode and inspect JWT token header and payload
QR Code Generator
Generate QR codes from text or URLs and download as PNG
Text Tools (5)
Character Counter
Count characters, words, sentences, lines and bytes
Case Converter
Convert text to UPPER, lower, Title, camelCase, snake_case and more
Lorem Ipsum Generator
Generate placeholder Lorem Ipsum text for design and development
Slug Generator
Convert text to URL-friendly slugs
Text Diff Checker
Compare two texts and highlight the differences line by line
Color Tools (2)
Math & Calculators (4)
Percentage Calculator
Calculate percentages, increases and decreases
BMI Calculator
Calculate Body Mass Index with metric and imperial units
Age Calculator
Calculate exact age in years, months, and days from date of birth
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal