Show HN Daily Selection (2025-04-26)
- I used OpenAI's new image API for a personalized coloring book service
- Formalizing Principia Mathematica using Lean
- Magnitude – open-source, AI-native test framework for web apps
- A modern spreadsheet with Python integration
- BugStalker - a modern Rust debugger
- RSS Lookup – Find RSS Feeds for Any URL (Free, Open Source)
- Faasta – A self-hosted Serverless platform for WASM-wasi-HTTP in Rust
- StackHound - Stop guessing repo's tech stack, analyze it in seconds
- SnipFast – Extract Highlighted Text from Physical Books
- An interactive demo of QR codes' error correction
- Claude Code with GUI and Block Based Prompt Editor (MIT)
- Loat – Grow MRR with automated emails
- An MCP Server for Understanding AWS Costs
- OpenWrt Configurator – Simple config management for OpenWrt devices
- Turn Rails REST APIs into Model Context Protocol (MCP) Servers
- Pomo – Manage your Stripe promo codes without code
- Mailfrom.dev – A Cheaper MailTrap Alternative
- My Python text-based dungeon crawler game engine
- TSCE – Think Before You Speak (Two-Step Contextual Enrichment for LLMs)
- Mermaid Open Editor 2.0
- Turbine – A scripting language for C/C++ with Markdown-like syntax
I used OpenAI's new image API for a personalized coloring book service [Image]
46 points, 26 comments
A service that generates personalized coloring books from family photos using OpenAI's image API.
- Uses OpenAI's image API to automate the creation of coloring book pages from uploaded photos
- Integrates with printing services to deliver physical coloring books
- Appeals to both adults and kids for creative and cathartic enjoyment
- Offers a 10% discount for early users
Discussion Link, Original Link
Formalizing Principia Mathematica using Lean [Research]
84 points, 21 comments
A project to formalize Bertrand Russell's Principia Mathematica using the Lean theorem prover, adhering closely to the original proofs.
- Formalizes the first volume of Principia Mathematica using Lean4
- Follows Russell's proofs rigorously with minimal added statements
- Aims for high accuracy and welcomes feedback on inaccuracies
- Inspired by but distinct from an existing Coq-based formalization
- Open-source and available on GitHub for collaboration
Discussion Link, Original Link
Magnitude – open-source, AI-native test framework for web apps [Developer Tools]
113 points, 30 comments
An open-source, AI-native test framework for web apps using visual LLM agents for faster, cheaper, and more reliable testing.
- Uses pure vision instead of error-prone "set-of-marks" systems
- Employs tiny VLM (Moondream) for faster and cheaper execution than OpenAI/Anthropic
- Features two-agent system: planner for adapting test cases and executor for quick, consistent runs
- Saves and reuses test plans for efficiency, with fallback to planner if issues arise
- Fully open-source and optimized specifically for web testing
Discussion Link, Original Link
A modern spreadsheet with Python integration [Productivity]
44 points, 6 comments
A modern spreadsheet tool with Python integration for handling large datasets efficiently.
- Processes large datasets (4GB+) and loads GB/32 million-row files in seconds
- Supports up to 500GB RAM usage without crashes
- Edits, splits, merges, and cleans CSV/text files with up to 32M rows and 1M columns
- Allows Python functions as UDF formulas, returning images or CSV files
- Includes statistical pivot data functions and solver functions with virtually no variable limits
- Generates charts instantly with millions of data points
- Actively incorporates user feedback for improvements
Discussion Link, Original Link
BugStalker - a modern Rust debugger [Developer Tools]
103 points, 15 comments
A modern Rust debugger written in Rust.
- Modern debugger for Rust
- Written in Rust itself
- Designed for debugging Rust applications
Discussion Link, Original Link
RSS Lookup – Find RSS Feeds for Any URL (Free, Open Source) [Developer Tools]
4 points, 3 comments
A free, open-source tool to find RSS feeds for any URL by analyzing meta tags, fallback paths, and hardcoded feeds.
- Automatically searches for RSS feeds from any website URL
- Uses meta tags, fallback paths, and hardcoded feeds for popular sites
- Open-source with no ads or URL tracking
- Includes Cloudflare Turnstile for abuse prevention and Plausible for analytics
Discussion Link, Original Link
Faasta – A self-hosted Serverless platform for WASM-wasi-HTTP in Rust [Developer Tools]
86 points, 30 comments
Faasta is a self-hosted serverless platform for WASM-wasi-HTTP functions, written in Rust, offering efficient multi-tenancy and high concurrency.
- Open-source and standards-compliant WASI-HTTP hosting
- Enables thousands of concurrent function invocations in a single process
- CLI utility available via
cargo install cargo-faasta - Free hosted instance with GitHub OAuth deployment (10-function limit per account)
- More efficient than traditional VM-based serverless solutions like AWS Lambda
Discussion Link, Original Link
StackHound - Stop guessing repo's tech stack, analyze it in seconds [Developer Tools]
5 points, 1 comments
StackHound analyzes GitHub repos to reveal their actual tech stack by scanning dependency files.
- Scans dependency files to uncover tools, frameworks, and languages
- Works with React, Next.js, Tailwind, Flask, Spring Boot, and more
- Instant analysis by entering a GitHub username and repo
- Provides an API endpoint for integration into custom tools
- Open-source and includes a live demo
Discussion Link, Original Link
SnipFast – Extract Highlighted Text from Physical Books [Education]
9 points, 0 comments
A tool for extracting highlighted text from physical books via image capture.
- Automatically detects and extracts highlighted text from page photos
- Allows manual selection of sentences for precise copying
- Uses a custom ML model for highlight detection
- Free trial with credits, followed by small payment to prevent abuse
- Designed for readers, students, and researchers
- Kotlin backend with Postgres database
- Early-stage feedback sought for UI and usability improvements
Discussion Link, Original Link
An interactive demo of QR codes' error correction [Consumer Tech]
10 points, 2 comments
Interactive demo showcasing QR code error correction by allowing users to draw on QR codes and see real-time damage impact.
- Visualizes QR code error tolerance with health bars and damage counters
- Toggle between draw mode and inspect mode for detailed analysis
- Uses WebAssembly-compiled C++ decoder for accurate real-time feedback
- Encourages verification via phone scanning to confirm breakpoints
- Demonstrates QR code resilience with minimal data region damage challenge
Discussion Link, Original Link
Claude Code with GUI and Block Based Prompt Editor (MIT) [Developer Tools]
3 points, 1 comments
Claude Code offers a GUI and block-based prompt editor for coding with Claude.
- Features a graphical user interface (GUI)
- Includes a block-based prompt editor
- Open-source under MIT license
Discussion Link, Original Link
Loat – Grow MRR with automated emails [Marketing]
4 points, 2 comments
Loat is a platform for founders to automate email campaigns for growth and onboarding without needing a dedicated CRM.
- Automates email sequences for different products
- Supports educational nurture campaigns and newsletters
- Designed for lean teams to maximize email as a growth channel
- Built from internal tools used in a high-trust tax product
Discussion Link, Original Link
An MCP Server for Understanding AWS Costs [Finance]
14 points, 3 comments
An MCP Server that connects LLMs like Claude and Cursor to AWS cost and usage data via the Vantage API for AI-driven cloud cost management.
- Integrates with LLMs (Claude, Cursor, with ChatGPT and Gemini coming soon)
- Supports 20+ cloud providers (AWS, Datadog, MongoDB, etc.)
- Enables ad-hoc cost queries, action plans, and multi-tool workflows
- Requires a Vantage account for API access
- Open-source (GitHub repo available)
OpenWrt Configurator – Simple config management for OpenWrt devices [Developer Tools]
3 points, 0 comments
A CLI tool for easy configuration management of OpenWrt devices, with plans for a web UI and open-source UniFi Controller alternative.
- Simplifies provisioning configurations across multiple OpenWrt devices
- CLI-based for quick and scriptable management
- Future plans include a web UI for enhanced usability
- Aims to be an open-source alternative to UniFi Controller
Discussion Link, Original Link
Turn Rails REST APIs into Model Context Protocol (MCP) Servers [Developer Tools]
3 points, 0 comments
Turn Rails REST APIs into Model Context Protocol (MCP) Servers.
- Converts Rails REST APIs to MCP servers
- Enhances API functionality with model context protocol
Discussion Link, Original Link
Pomo – Manage your Stripe promo codes without code [Business]
4 points, 6 comments
A free tool to batch create and manage Stripe promo codes without coding.
- No-code solution for creating unique promo codes in Stripe
- Batch generation with customizable prefixes
- Simple setup using Stripe API keys
- Export promo codes for marketing campaigns
Discussion Link, Original Link
Mailfrom.dev – A Cheaper MailTrap Alternative [Developer Tools]
3 points, 2 comments
A simple, affordable sandbox SMTP server for testing email flows in dev/staging environments without sending real emails.
- Affordable alternative to MailTrap
- Easy setup and sharing with team/clients
- Supports testing email flows (resets, onboarding, verifications)
- Built with Laravel, Vue 3, shadcn, hosted on k3s (Hetzner)
- Uses AWS S3 and SES for storage and email handling
Discussion Link, Original Link
My Python text-based dungeon crawler game engine [Entertainment]
3 points, 0 comments
A Python-based text dungeon crawler engine created during recovery from surgery.
- Game worlds defined in JSON
- Includes rooms, loot, and monsters
- Open-source on GitHub
TSCE – Think Before You Speak (Two-Step Contextual Enrichment for LLMs) [Developer Tools]
3 points, 0 comments
TSCE is a Python library that enhances small language models' instruction-following precision using a two-step architecture without fine-tuning.
- No fine-tuning required, works with existing models like GPT-3.5 and GPT-4
- Improves reliability by separating thinking (Phase 1) and answering (Phase 2)
- Compatible with OpenAI and Azure OpenAI APIs
- Minimal latency overhead (~2 API calls) for clearer, more accurate outputs
- Customizable system prompts for tailored responses
Discussion Link, Original Link
Mermaid Open Editor 2.0 [Developer Tools]
3 points, 1 comments
Mermaid Open Editor 2.0 is an updated version of the open-source Mermaid diagram editor.
- Open-source
- Supports Mermaid diagram creation
- Enhanced features in version 2.0
Discussion Link, Original Link
Turbine – A scripting language for C/C++ with Markdown-like syntax [Developer Tools]
3 points, 0 comments
A scripting language for C/C++ with Markdown-like syntax, designed for easy embedding and readability.
- Designed for embedding in C/C++ with minimal overhead
- Uses Markdown-inspired syntax for readability
- Includes built-in container types (vec, set, map)
- Provides a straightforward C API for integration