Tools
Small things, free, no sign-up.
Each one came out of a system I was working on and was easier to build than to keep explaining. They run entirely in your browser — nothing you type is sent anywhere.
Rate limiter playground
Run six rate limiting algorithms against bursty, scraping and thundering-herd traffic, watch what each one blocks, and copy the nginx, Express, NestJS or Redis config that implements it.
Token bucketSliding windownginxRedis
OpenColour picker
One colour, two readings — as a highlight behind black text and as a flat fill, with the contrast ratio against near-black underneath.
HexHSLWCAG contrast
OpenAI Token Cost Calculator
Estimate your LLM API spend across OpenAI, Claude, and Gemini using current token pricing.
LLMAPI CostTokens
OpenOpenAI Cost Calculator
Calculate exact costs for GPT-4o, GPT-4 Turbo, and O1 models.
OpenAIGPT-4oPricing
OpenClaude Cost Calculator
Estimate spend for Claude 3.5 Sonnet, Opus, and Haiku.
AnthropicClaude 3.5Pricing
OpenGemini Cost Calculator
Calculate costs for Gemini 1.5 Pro and Flash models.
Google AIGemini 1.5Pricing
OpenAI Image Cost Calculator
Compare cost of AI image generation across Midjourney, DALL-E, and Stable Diffusion.
Image GenDALL-EMidjourney
OpenAI Video Cost Calculator
Estimate spend for AI video generation based on duration and provider.
Video GenSoraRunway
OpenAI Prompt Generator
Craft high-quality structured prompts using personas, constraints, and clear goals.
Prompt EngineeringLLM
OpenJSON Formatter
Format, validate, and minify JSON strings to stop squinting at API responses.
JSONDeveloper Tool
OpenResume ATS Checker
Check if your resume is ATS-friendly and optimize keywords to get past the bots.
CareerATSResume
OpenAI ROI Calculator
Determine if AI automation is saving you money by comparing human hours vs API costs.
BusinessROIAutomation
OpenSaaS Pricing Calculator
Model your MRR, churn, and LTV to determine a sustainable price point.
SaaSPricingMRR
OpenContext Window Calculator
Measure text in tokens and see how it fits into various LLM context windows.
LLMContextTokens
OpenCPM Calculator
Calculate Cost Per Mille to measure the efficiency of your ad spend.
AdsMarketingCPM
OpenYouTube Revenue Calculator
Predict revenue based on views, CPM, and niche for YouTube content.
YouTubeRevenueCPM
Open