🛠️ All DevTools

[Testing] Show HN: VaultSandbox – Test your real MailGun/SES/etc. integration I&#x27;ve spent the last few months working on something I wish I&#x27;d had years ago. I kept running into the same issue: CI green, production mail broken. TLS handshake failures, DKIM alignment mismatches, SPF soft-fails ... the stuff that only surfaces when real mail servers are involved. Most test tools (Mailpit, MailHog) are catch-alls. They confirm &quot;an email was sent&quot; but don&#x27;t validate the protocol. They also aren&#x27;t designed for network-exposed environments: no auth, unprotected Web UI, easy to enumerate messages.<p>VaultSandbox is my attempt at fixing that. It&#x27;s a self-hosted SMTP gateway (AGPLv3) that validates SPF, DKIM, DMARC, and rDNS on every incoming message. You keep your production email provider (Postmark, SendGrid, SES) in tests and you just change the recipient domain. No mocking, no config changes. There are client SDKs (Node, Python, Go, Java, .NET), plus a Web UI and a CLI for manual testing.<p>Some technical details:<p>Deterministic Tests Instead of polling or sleep loops, the SDKs use Server-Sent Events (SSE) so test assertions trigger the moment the mail hits the gateway.<p>Minimal infrastructure footprint Built with NestJS and Angular, with no external database dependency to keep the container footprint small and easier to reason about.<p>Post-Quantum Encryption I use ML-KEM-768 for the encryption layer. Incoming mail is encrypted immediately using a client-generated public key and the plaintext is discarded. The server only ever stores encrypted message data and cannot decrypt it. I chose PQ because I wanted to build something I wouldn&#x27;t have to revisit in five years. If it handles large PQ keys reliably, everything else is easy.<p>Quick start: <a href="https:&#x2F;&#x2F;vaultsandbox.dev&#x2F;getting-started&#x2F;quickstart&#x2F;" rel="nofollow">https:&#x2F;&#x2F;vaultsandbox.dev&#x2F;getting-started&#x2F;quickstart&#x2F;</a><p>Site: <a href="https:&#x2F;&#x2F;vaultsandbox.com" rel="nofollow">https:&#x2F;&#x2F;vaultsandbox.com</a><p>I&#x27;d love feedback, especially on whether AGPLv3 would be a blocker for something you&#x27;d self-host in dev.

[Other] Show HN: Mantic.sh – A structural code search engine for AI agents Author here! Some context: I published this 48 hours ago and it was auto-listed on MCPMarket (the MCP tools directory). Got 700+ organic downloads with zero marketing—developers were actively searching for exactly this solution.<p>The &quot;Git Accelerator&quot; optimization story:<p>Initially used a file walker that took 6.6s on Chromium. Profiling showed 90% was filesystem I&#x2F;O. The fix: git ls-files returns 480k paths in ~200ms. Added smart heuristics for untracked files (only scan dirs &lt;50k files), bringing total to 0.46s.<p>Why this matters: Agents can&#x27;t wait 10 seconds for search. Sub-500ms makes it feel instant, changing how they explore codebases.<p>Installation:<p><pre><code> Cursor: npx mantic.sh@latest VS Code: npx mantic.sh@latest CLI: npm i -g mantic.sh </code></pre> Limitations: Mantic is optimized for precise queries (&quot;find stripe webhook&quot;) where structure matters. For fuzzy exploratory search, traditional embeddings may still be better. Curious if HN has ideas for hybrid approaches.<p>Happy to answer questions!

[Other] Show HN: Similarity = cosine(your_GitHub_stars, Karpathy) Client-side GitHub profile analysis - Build your embedding from your Stars - Compare and discover popular people with similar interests and share yours - Generate a Skill Radar - Recommend repositories you might like

[Other] Show HN: Prism.Tools – Free and privacy-focused developer utilities Hi HN, I&#x27;m Barry and I&#x27;ve built Prism.Tools (<a href="https:&#x2F;&#x2F;blgardner.github.io&#x2F;prism.tools&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blgardner.github.io&#x2F;prism.tools&#x2F;</a>) – a collection of client-side developer utilities that respect your privacy.<p>Many of these tools were used way back in the days when I ran a BBS and started my communities first ISP, serving three local communities with Dial-Up Internet, Web Hosting etc. The tools have been refined to reflect the changes in tech since then and designed for the Novice and Pro alike. As I locate more tools others may find useful I will refine and add them to the collection. Use them, Share them, or not. They will be here if you need them...<p>40+ dev tools (JSON formatters, regex tester, base64 encoder, Git command helper, etc.) that run entirely in your browser. Zero tracking, zero analytics, zero data collection – everything processes locally. Self-contained HTML files with no build process or frameworks.<p>I realized I had a lot of tools&#x2F;utilities I&#x27;ve built over the years for my own use. I lothe having to &#x27;sign-up&#x27; just to access&#x2F;use simple utilities that I can create myself. I&#x27;ve refined them and put them in one safe place so I could easily access them if&#x2F;when needed. I decided to make them available via Github Pages for anyone that may find them useful. Prism.Tools is the result.<p>Each tool is a standalone HTML file with embedded CSS and JavaScript. No frameworks, no npm packages, no build steps – just open the file and it works.<p>The entire toolset:<p>- 100% client-side processing – your data never leaves your browser.<p>- No external dependencies except for specific libraries from cdnjs.cloudflare.com (marked.js for markdown, exifr for image metadata, etc.)<p>- Consistent dark UI – every tool follows the same design language for familiarity.<p>- Vanilla JS where possible – only reaching for Public CDN Resources when necessary.<p>The constraint of &quot;single HTML file&quot; was intentional. It forces simplicity and ensures tools remain maintainable. It also means users can inspect, modify, or self-host any tool trivially.<p>These tools have helped me with debugging production issues, Quick formatting tasks, learning Git commands (the Git command helper has been particularly helpful)<p>Just visit <a href="https:&#x2F;&#x2F;blgardner.github.io&#x2F;prism.tools&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blgardner.github.io&#x2F;prism.tools&#x2F;</a> and try any tool. No signup, no install.<p>What tools are missing that you find yourself needing? Any performance issues with specific tools? UI&#x2F;UX friction points?<p>All tools follow the same privacy-first philosophy... Your data stays in your browser. No accounts, no tracking, no servers processing your information. The project is also a demonstration that you don&#x27;t always need React, Vue, or complex build pipelines – sometimes vanilla JavaScript in a single HTML file is exactly the right tool for the job.<p>Vanilla JavaScript (ES6+) CSS3 with CSS Grid Minimal external libraries: marked.js, exifr, highlight.js, sql-formatter (all from CDN) No frameworks, no bundlers, no npm Hosted on Github Pages<p>Happy to answer questions about the technical implementation, design decisions, or specific tools!<p>All tools are inspectable – just view source on any page to see exactly how they work!

[CLI Tool] Run multiple claude-code agents from YAML config Cortex is an AI agent orchestrator CLI that lets you design deterministic, multi-agent workflows using simple YAML files. Unlike chat-based tools, it supports true parallel execution, task dependencies, and output chaining between agents. Cortex introduces infrastructure-style configs (Cortexfile & MasterCortex) to orchestrate single or multi-project AI workflows with real-time streaming, session tracking, and reproducible runs—built for developers who want control, scalability, and automation.

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[API/SDK] Schedule API calls and get results delivered, no cron needed Schedule API calls instantly — get results & alerts without cron, servers, or workflows

[API/SDK] Open Source Video Encoding API Service An open source, FFmpeg-based video encoding API that supports multiple concurrent instances. Easily scale video processing with parallel encoding, efficient resource management, and flexible API endpoints for a reliable, production-ready solution.

[Other] Transform Claude Code into a production dev environment. AIKit is an open-source toolkit that supercharges Claude Code (Anthropic's official CLI) and OpenCode with structured workflows, visual diagramming, task tracking, and automated quality gates. Built for developers who want reliable, repeatable AI-powered development.

[CLI Tool] Show HN: VPS marketplace for 5 Clouds in Yer Terminal

[Code Quality] Show HN: RepoReaper – AST-aware, JIT-loading code audit agent (Python/AsyncIO) OP here. I built RepoReaper to solve code context fragmentation in RAG.<p>Unlike standard chat-with-repo tools, it simulates a senior engineer&#x27;s workflow: it parses Python AST for logic-aware chunking, uses a ReAct loop to JIT-fetch missing file dependencies from GitHub, and employs hybrid search (BM25+Vector). It also generates Mermaid diagrams for architecture visualization. The backend is fully async and persists state via ChromaDB.<p>Link: <a href="https:&#x2F;&#x2F;github.com&#x2F;tzzp1224&#x2F;RepoReaper" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;tzzp1224&#x2F;RepoReaper</a>

[Other] Show HN: Memory Graph – Interactive Python execution and memory visualizer Hello everybody,<p>I built Memory Graph to help students (and myself) build a correct mental model of Python references, mutability, and copying, and to make debugging data structures less “print-driven”. It’s inspired by Python Tutor, but focuses on clearer graphs and on running locally in many different environments and debuggers. The Memory Graph Web Debugger quickly turns your web browser into a Python debugger where the whole program state is visualized in each step, clearly showing aliasing and the structure of the data, giving insight that is hard to get with just printing.<p>Some interesting examples:<p>- Recursion, decimal to binary conversion: <a href="https:&#x2F;&#x2F;memory-graph.com&#x2F;#codeurl=https:&#x2F;&#x2F;raw.githubusercontent.com&#x2F;bterwijn&#x2F;memory_graph&#x2F;refs&#x2F;heads&#x2F;main&#x2F;src&#x2F;binary_convert.py&amp;timestep=1.0&amp;play" rel="nofollow">https:&#x2F;&#x2F;memory-graph.com&#x2F;#codeurl=https:&#x2F;&#x2F;raw.githubusercont...</a><p>- Binary Tree data structure: <a href="https:&#x2F;&#x2F;memory-graph.com&#x2F;#codeurl=https:&#x2F;&#x2F;raw.githubusercontent.com&#x2F;bterwijn&#x2F;memory_graph&#x2F;refs&#x2F;heads&#x2F;main&#x2F;src&#x2F;bin_tree.py&amp;timestep=0.2&amp;play" rel="nofollow">https:&#x2F;&#x2F;memory-graph.com&#x2F;#codeurl=https:&#x2F;&#x2F;raw.githubusercont...</a><p>- Cocktail Shaker Sort: <a href="https:&#x2F;&#x2F;memory-graph.com&#x2F;#codeurl=https:&#x2F;&#x2F;raw.githubusercontent.com&#x2F;bterwijn&#x2F;memory_graph&#x2F;refs&#x2F;heads&#x2F;main&#x2F;src&#x2F;cocktail_sort.py&amp;breakpoints=16,45&amp;continues=1&amp;timestep=0.2&amp;play" rel="nofollow">https:&#x2F;&#x2F;memory-graph.com&#x2F;#codeurl=https:&#x2F;&#x2F;raw.githubusercont...</a><p>Here you can find some difficult Python Data Model exercises for use in education where Memory Graph helps explain the correct answer:<p><pre><code> https:&#x2F;&#x2F;github.com&#x2F;bterwijn&#x2F;memory_graph_videos&#x2F;blob&#x2F;main&#x2F;exercises&#x2F;exercises.md</code></pre>

[Other] Show HN: WOLS – Open standard for mushroom cultivation tracking I built an open labeling standard for tracking mushroom specimens through their lifecycle (from spore&#x2F;culture to harvest).<p>v1.1 adds clonal generation tracking (distinct from filial&#x2F;strain generations) and conforms to JSON-LD for interoperability with agricultural&#x2F;scientific data systems.<p>Spec (CC 4.0): <a href="https:&#x2F;&#x2F;wemush.com&#x2F;open-standard&#x2F;specification" rel="nofollow">https:&#x2F;&#x2F;wemush.com&#x2F;open-standard&#x2F;specification</a> Client libraries (Apache 2.0): Python + CLI: pip install wols (also on GHCR) TypeScript&#x2F;JS: npm install @wemush&#x2F;wols<p>Background: Mycology has fragmented data practices (misidentified species, inconsistent cultivation logs, no shared vocabulary for tracking genetics across generations). This is an attempt to fix that.<p>Looking for feedback from anyone working with biological specimen tracking, agricultural data systems, or mycology.

[Other] Show HN: Open-Source 8-Ch BCI Board (ESP32 and ADS1299 and OpenBCI GUI) Hi HN, I recently shared this on r&#x2F;BCI and wanted to see what the engineering community here thinks.<p>A while back, I got frustrated with the state of accessible BCI hardware. Research gear was wildly unaffordable. So, I spent a ton of time designing a custom board, software and firmware to bridge that gap. I call it the Cerelog ESP-EEG. It is open-source (Firmware + Schematics), and I designed it specifically to fix the signal integrity issues found in most DIY hardware.<p>I believe in sharing the work. You can find the Schematics, Firmware, and Software setup on the GitHub repo: GITHUB LINK: <a href="https:&#x2F;&#x2F;github.com&#x2F;Cerelog-ESP-EEG&#x2F;ESP-EEG" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;Cerelog-ESP-EEG&#x2F;ESP-EEG</a><p>For those who don&#x27;t want to deal with BGA soldering or sourcing components, I do have assembled units available: <a href="https:&#x2F;&#x2F;www.cerelog.com&#x2F;eeg_researchers.html" rel="nofollow">https:&#x2F;&#x2F;www.cerelog.com&#x2F;eeg_researchers.html</a><p>The major features: Forked&#x2F;modified OpenBCI GUI Compatibility as well as Brainflow API, and LSL Compatibility. I know a lot of us rely on the OpenBCI GUI for visualization because it just works. I didn&#x27;t want to reinvent the wheel, so I ensured this board supports it natively.<p>It works out of the box: I maintain a forked modified version of the GUI that connects to the board via LSL (Lab Streaming Layer). Zero coding required: You can visualize FFTs, Spectrograms, and EMG widgets immediately without writing a single line of Python.<p>The &quot;active bias&quot; (why my signal is cleaner): The TI ADS1299 is the gold standard for EEG, but many dev boards implement it incorrectly. They often leave the Bias feedback loop &quot;open&quot; (passive), which makes them terrible at rejecting 60Hz mains hum. I simply followed the datasheet: I implemented a True Closed-Loop Active Bias (Drive Right Leg).<p>How it works: It measures the common-mode signal, inverts it, and actively drives it back into the body. The result: Cleaner data<p>Tech stack:<p><pre><code> ADC: TI ADS1299 (24-bit, 8-channel). MCU: ESP32 Chosen to handle high-speed SPI and WiFi&#x2F;USB streaming Software: BrainFlow support (Python, C++, Java, C#) for those who want to build custom ML pipelines, LSL support, and forked version of OpenBCI GUI support </code></pre> This was a huge project for me. I’m happy to geek out about getting the ESP32 to stream reliably at high sample rates as both the software and firmware for this project proved a lot more challenging than I expected. Let me know what you think!<p>SAFETY NOTE: I strongly recommend running this on a LiPo battery via WiFi. If you must use USB, please use a laptop running on battery power, not plugged into the wall.

[Other] Show HN: OSS sustain guard – Sustainability signals for OSS dependencies Hi HN, I made OSS Sustain Guard.<p>After every high-profile OSS incident, I wonder about the packages I rely on right now. I can skim issues&#x2F;PRs and activity on GitHub, but that doesn’t scale when you have tens or hundreds of dependencies. I built this to surface sustainability signals (maintainer redundancy, activity trends, funding links, etc.) and create awareness. It’s meant to start a respectful conversation, not to judge projects. These are signals, not truth; everything is inferred from public data (internal mirrors&#x2F;private work won’t show up).<p>Quick start: pip install oss-sustain-guard export GITHUB_TOKEN=... os4g check<p>It uses GitHub GraphQL with local caching (no telemetry; token not uploaded&#x2F;stored), and supports multiple ecosystems (Python&#x2F;JS&#x2F;Rust&#x2F;Go&#x2F;Java&#x2F;etc.).<p>Repo: <a href="https:&#x2F;&#x2F;github.com&#x2F;onukura&#x2F;oss-sustain-guard" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;onukura&#x2F;oss-sustain-guard</a><p>I’d love feedback on metric choices&#x2F;thresholds and wording that stays respectful. If you have examples where these signals break down, please share.

[Other] I switched from VSCode to Zed

[Other] JSON made simple, powered by AI JSON Editor is the ultimate online playground for JSON. Format, minify, compare, and visualize JSON instantly in a beautiful tree view built for speed and clarity. Supercharge your workflow with an AI chat assistant that helps you analyze, edit, and understand complex data in seconds. Keep multiple JSON files saved forever in your browser, organized in tabs—just like your favorite IDE, VS Code, but for the web — powerful, intuitive, and completely free.

[CLI Tool] Next-Gen AI-Powered Programming Terminal ELFTERM is a modern, professional terminal application designed specifically for AI developers. It not only supports powerful multi-window split-screen functionality but also integrates an intelligent Prompt Workbench to help developers improve efficiency and build a personal command knowledge base. Whether for daily development, server management, or AI-assisted programming, ELFTERM makes your work more elegant and efficient.

[Other] AI that knows when you're tired - blocks dangerous commands Humsana MCP detects your cognitive state (focus, stress, fatigue) from typing patterns and provides this context to AI assistants like Claude, Cursor, and Continue.dev. Cognitive Interlock blocks dangerous commands when you're too tired to think straight. Everything runs locally. No data leaves your machine. Install via: npx @humsana/mcp-server We're onboarding developers who want Cognitive Interlock and advanced features. DM or comment if you want early access.

[Other] Social media you can query with SQL A social media platform built for developers who think in SQL. No algorithmic feeds. No hidden engagement tricks. Just you, a terminal-style interface, and pure SQL.