$ devtoolkit.sh

Build structured AI prompts with role, task, context, and output format fields.

Build AI API request payloads and cURL commands for any provider.

Count tokens for GPT, Claude, Gemini, and LLaMA models.

Encode text or binary data to Base64 format.

Turn code snippets into beautiful shareable images with a window chrome and syntax highlighting.

Pretty-print and format JSON with proper indentation.

Check if your prompts fit within any AI model context window.

Estimate AI API costs for GPT, Claude, Gemini, and LLaMA.

Detect hedging, refusal, truncation, repetition, and format violations in LLM output.

Extract and fix JSON from mixed LLM output — handles prose, markdown, and concatenation.

Fix broken LLM JSON: strip markdown fences, trailing commas, single quotes, and more.

Visually build JSON schemas for AI function calling and structured output.

Build structured AI prompts with role, task, context, and output format fields.

Automatically check your prompt against 7 prompt-engineering best practices.

Analyze and improve AI prompts with rule-based suggestions.

Build AI API request payloads and cURL commands for any provider.

Count tokens for GPT, Claude, Gemini, and LLaMA models.

Generate all standard iOS and Android app icon sizes from a single source image.

Decode Base64-encoded strings back to readable text.

Encode text or binary data to Base64 format.

Convert multiple images to JPEG, PNG, or WebP at once with a shared quality setting and individual download buttons.

Calculate token usage against Claude up to 1M context windows.

Calculate Anthropic Claude API costs for Sonnet, Opus, and Haiku.

Build structured system prompts for Anthropic Claude using XML tags.

Build Anthropic Messages API request payloads and cURL commands.

Count tokens for Claude Sonnet 4.6, Opus, and Haiku models.

Turn code snippets into beautiful shareable images with a window chrome and syntax highlighting.

Convert CSV data to a JSON array of objects.

Generate SHA-1, SHA-256, SHA-384, and SHA-512 cryptographic hashes from any text.

Convert HEX color codes to RGB and HSL values with a live preview.

Compress images by adjusting JPEG quality to reduce file size without leaving your browser.

Upload an image and compare its file size as JPEG, PNG, and WebP side by side to pick the best format.

Resize images to exact dimensions with optional aspect ratio lock, entirely in your browser.

Convert any image to WebP format with a quality slider and file size comparison.

Resize and crop images to Instagram post, portrait, landscape, and story dimensions.

Convert JPEG images to WebP format with a quality slider — runs entirely in your browser.

Compare two JSON objects and highlight added, removed, and changed keys.

Pretty-print and format JSON with proper indentation.

Test JSONPath expressions against JSON data and see matched results.

Convert a JSON array of objects to CSV format.

Convert JSON to YAML format with proper indentation.

Check if your JSON is valid and find syntax errors.

Decode and inspect JSON Web Token header and payload.

Generate Lorem Ipsum placeholder text for mockups and prototypes.

Live Markdown editor with side-by-side HTML preview.

Convert Markdown text to clean HTML markup.

Check if your prompts fit within GPT-4o and GPT-3.5 context windows.

Calculate GPT-4o, GPT-4.1, and GPT-3.5 API costs.

Build structured system prompts for ChatGPT and GPT-4o.

Build OpenAI Chat Completions API request payloads and cURL commands.

Count tokens for GPT-4o, GPT-4.1, and GPT-3.5 models.

Generate strong, random passwords with customizable options.

Analyze password strength by checking length, character variety, and entropy.

Real-time collaborative estimation for agile teams. Create a room, share the link, pick cards, reveal together.

Test regular expressions against text with real-time match highlighting.

Real-time collaborative retrospective board for agile teams. Add cards, vote, discuss, create action items.

Convert text to a URL-friendly slug instantly.

Reference table of image dimensions for every major social media platform.

Convert Unix timestamps to human-readable dates and vice versa.

Show a date and time across multiple timezones simultaneously.

Decode percent-encoded URL strings back to readable text.

Encode text for safe use in URLs using percent-encoding.

Generate random UUIDs (v4) for use as unique identifiers.

Generate a unique URL to capture and inspect incoming HTTP requests in real time.

Count words, characters, sentences, and lines in any text.

Convert YAML to JSON with proper structure and types.

Create a 1280×720 YouTube thumbnail with a background image and bold title text overlay.

Calculate total AI API costs across multiple models and request volumes.

Design multi-step AI prompt chains with variable references between steps.

Split text into token-sized chunks with configurable overlap for RAG and embedding pipelines.

Check if your prompts fit within any AI model context window.

Estimate AI API costs for GPT, Claude, Gemini, and LLaMA.

Parse AI API cURL commands and extract structured request details.