https://jonlu.ca Essays by JonLuca DeCaro about programming, reverse engineering, product systems, travel, and technology. https://jonlu.ca/posts/http-headers-top-1000 https://jonlu.ca/posts/http-headers-top-1000 I crawled the top 1,000 sites and read their response headers. Browser fossils, CDN breadcrumbs, leaked codenames, a snowman, and a tribute to Terry Pratchett. Sat, 30 May 2026 19:33:57 GMT https://jonlu.ca/posts/smoothing-the-jagged-frontier https://jonlu.ca/posts/smoothing-the-jagged-frontier AI models may bring back the ability to combine deep expertise from every field toward a single goal. Sun, 24 May 2026 01:20:00 GMT https://jonlu.ca/posts/vibecoding-native-apps https://jonlu.ca/posts/vibecoding-native-apps I built a fine dining tracker app using React Native, and the experience was surprisingly smooth, both from how good React Native has gotten, and how much better the models are. Mon, 02 Feb 2026 03:34:03 GMT https://jonlu.ca/posts/markets-are-the-ultimate-rl-environment https://jonlu.ca/posts/markets-are-the-ultimate-rl-environment Why financial markets are an unusually pure, brutal, and adversarial reinforcement learning environment. Sat, 13 Dec 2025 23:58:52 GMT https://jonlu.ca/posts/skycards https://jonlu.ca/posts/skycards Automating SkyCards, the FlightRadar24 plane‑spotting game Fri, 12 Sep 2025 01:50:21 GMT https://jonlu.ca/posts/ca-plate-checker https://jonlu.ca/posts/ca-plate-checker Reverse engineering the California DMV's license plate availability checker to find cool custom plates. Thu, 28 Aug 2025 20:26:40 GMT https://jonlu.ca/posts/optimizing-model-load-times https://jonlu.ca/posts/optimizing-model-load-times Improving PyTorch model loading performance using memory-based filesystems and distributed storage in Kubernetes. Sat, 03 May 2025 22:28:40 GMT https://jonlu.ca/posts/us-east-1-latency https://jonlu.ca/posts/us-east-1-latency Using latency measurements to infer when a globally used application is served only from us-east-1. Mon, 26 Jun 2023 16:26:53 GMT https://jonlu.ca/posts/magic-link https://jonlu.ca/posts/magic-link Examining passwordless Magic Link authentication and the implementation exposed in its onboarding flow. Wed, 31 May 2023 00:53:42 GMT https://jonlu.ca/posts/mimessage https://jonlu.ca/posts/mimessage Building semantic search and conversation analysis for an exported iMessage archive. Fri, 14 Apr 2023 04:31:20 GMT https://jonlu.ca/posts/verizon-rare-numbers https://jonlu.ca/posts/verizon-rare-numbers Automating Verizon number searches to find rare phone numbers with repeating digits. Sat, 28 May 2022 22:06:28 GMT https://jonlu.ca/posts/candy-machine https://jonlu.ca/posts/candy-machine Finding and disclosing vulnerabilities in Metaplex Candy Machine NFT minting contracts. Sat, 26 Feb 2022 23:59:43 GMT https://jonlu.ca/posts/heap-snapshot-scraping https://jonlu.ca/posts/heap-snapshot-scraping Using browser heap snapshots to recover structured data after network responses have been encrypted. Sun, 08 Aug 2021 21:06:09 GMT https://jonlu.ca/posts/javascript-facts https://jonlu.ca/posts/javascript-facts A tour of surprising JavaScript behavior involving functions, coercion, arrays, and language edges. Sun, 18 Jul 2021 13:18:39 GMT https://jonlu.ca/posts/async-python-http https://jonlu.ca/posts/async-python-http Controlling concurrency with asyncio and semaphores to make large batches of Python HTTP requests fast. Tue, 15 Jun 2021 03:02:29 GMT https://jonlu.ca/posts/vite https://jonlu.ca/posts/vite A minimal server-rendered starter setup for Vite, React 17, and TypeScript 4.3. Sun, 16 May 2021 16:49:29 GMT https://jonlu.ca/posts/hns-airdrop https://jonlu.ca/posts/hns-airdrop Claiming a Handshake developer airdrop and turning an unexpected token allocation into cash. Sun, 09 May 2021 21:22:33 GMT https://jonlu.ca/posts/apple-wifi https://jonlu.ca/posts/apple-wifi How Apple's large address allocation can interact unexpectedly with VPN routing and airplane Wi-Fi. Fri, 12 Mar 2021 16:03:51 GMT https://jonlu.ca/posts/tax-loss-harvesting https://jonlu.ca/posts/tax-loss-harvesting An accessible explanation of tax-loss harvesting, wash sales, and portfolio tradeoffs. Thu, 11 Mar 2021 00:39:59 GMT https://jonlu.ca/posts/zogo-zono https://jonlu.ca/posts/zogo-zono Reverse-engineering Zogo reward redemption requests and finding a profitable validation flaw. Wed, 20 Jan 2021 01:55:59 GMT https://jonlu.ca/posts/matomo-bypass https://jonlu.ca/posts/matomo-bypass Configuring self-hosted Matomo analytics behind custom routes and POST tracking. Thu, 17 Dec 2020 19:10:04 GMT https://jonlu.ca/posts/tmobile-wifi https://jonlu.ca/posts/tmobile-wifi Investigating an airline Wi-Fi authentication flow that granted T-Mobile connectivity. Sun, 29 Nov 2020 12:12:29 GMT https://jonlu.ca/posts/habitat https://jonlu.ca/posts/habitat A look back at living in a coliving community during the first year of COVID-19. Sat, 31 Oct 2020 21:06:30 GMT https://jonlu.ca/posts/american-airlines https://jonlu.ca/posts/american-airlines Examining how airline loyalty currencies shape American Airlines as much as flying passengers does. Sun, 06 Sep 2020 20:09:56 GMT https://jonlu.ca/posts/thoughts-on-product https://jonlu.ca/posts/thoughts-on-product Reflections on product engineering, growth work, experimentation, and building for user behavior. Sun, 30 Aug 2020 00:51:20 GMT https://jonlu.ca/posts/reversing-lyft https://jonlu.ca/posts/reversing-lyft Reverse-engineering Lyft's ride-history APIs to analyze six years of personal trips. Fri, 03 Jul 2020 23:20:34 GMT https://jonlu.ca/posts/nintendo-switch https://jonlu.ca/posts/nintendo-switch How the Nintendo Switch uses irreversible hardware fuses to prevent firmware downgrades. Sun, 14 Jun 2020 20:36:09 GMT https://jonlu.ca/posts/promises https://jonlu.ca/posts/promises Comparing Promise.all and Promise.allSettled for concurrent JavaScript workflows and failures. Thu, 14 May 2020 16:50:44 GMT https://jonlu.ca/posts/goodreads https://jonlu.ca/posts/goodreads Investigating why Goodreads pages responded slowly and what its requests revealed. Fri, 01 May 2020 06:45:21 GMT https://jonlu.ca/posts/reallowing-context https://jonlu.ca/posts/reallowing-context Restoring paste, context menu, and selection actions on websites that disable them. Wed, 01 Apr 2020 05:25:40 GMT https://jonlu.ca/posts/word-storage https://jonlu.ca/posts/word-storage Estimating the storage required to preserve every word humans have ever spoken. Sun, 09 Feb 2020 20:23:47 GMT https://jonlu.ca/posts/context-switches https://jonlu.ca/posts/context-switches Why small automations are valuable because they preserve focus, not merely because they save keystrokes. Sat, 18 Jan 2020 23:21:31 GMT https://jonlu.ca/posts/year-review https://jonlu.ca/posts/year-review A year of travel summarized through flights, mileage, routing, and memorable stops. Tue, 24 Dec 2019 13:17:28 GMT https://jonlu.ca/posts/aa-tracker https://jonlu.ca/posts/aa-tracker Investigating onboard flight entertainment APIs, flight telemetry, and Widevine-protected media. Sun, 22 Dec 2019 17:18:51 GMT https://jonlu.ca/posts/spf-dkim https://jonlu.ca/posts/spf-dkim Studying SPF, DKIM, and DMARC adoption and behavior across real-world email domains. Sat, 30 Nov 2019 02:26:11 GMT https://jonlu.ca/posts/safeway https://jonlu.ca/posts/safeway Reverse-engineering Safeway's coupon APIs to automate adding digital offers to an account. Sat, 12 Oct 2019 17:16:27 GMT https://jonlu.ca/posts/dsc-products https://jonlu.ca/posts/dsc-products Exploring an Ember application's data layer to find discontinued Dollar Shave Club products. Sun, 08 Sep 2019 00:10:04 GMT https://jonlu.ca/posts/churning-stats https://jonlu.ca/posts/churning-stats Scraping and analyzing activity patterns in the credit-card churning subreddit. Sat, 31 Aug 2019 22:49:35 GMT https://jonlu.ca/posts/tech-offers https://jonlu.ca/posts/tech-offers Analyzing compensation packages from 2019 new-graduate technology job offers. Mon, 29 Jul 2019 02:48:00 GMT https://jonlu.ca/posts/shell-shortcuts https://jonlu.ca/posts/shell-shortcuts A collection of practical shell aliases and functions for faster daily command-line work. Sun, 30 Jun 2019 01:55:46 GMT https://jonlu.ca/posts/clock https://jonlu.ca/posts/clock Using probability to compare a broken clock with one that is consistently five minutes slow. Sun, 02 Jun 2019 06:23:55 GMT https://jonlu.ca/posts/ana-rtw https://jonlu.ca/posts/ana-rtw Planning and taking an ANA round-the-world business-class award itinerary across Asia and Europe. Thu, 09 May 2019 04:49:13 GMT https://jonlu.ca/posts/window-vars https://jonlu.ca/posts/window-vars Finding application state and implementation clues by comparing unexpected browser global variables. Mon, 01 Apr 2019 01:22:31 GMT https://jonlu.ca/posts/experiments-and-growth-hacking https://jonlu.ca/posts/experiments-and-growth-hacking Inspecting exposed experiment APIs to understand how growth teams test product changes in production. Sat, 23 Feb 2019 20:16:46 GMT https://jonlu.ca/posts/deobfuscating-amex-scammer https://jonlu.ca/posts/deobfuscating-amex-scammer Reverse-engineering an obfuscated American Express phishing campaign from email to exfiltration endpoint. Sat, 02 Feb 2019 21:49:14 GMT https://jonlu.ca/posts/accidental-monetization https://jonlu.ca/posts/accidental-monetization How a student scheduling project drew a cease and desist and unexpectedly started earning money. Tue, 29 Jan 2019 03:57:33 GMT https://jonlu.ca/posts/uber-stats https://jonlu.ca/posts/uber-stats Building a Chrome extension to retrieve and analyze personal Uber trip history. Sat, 22 Dec 2018 15:39:48 GMT https://jonlu.ca/posts/ryan-air https://jonlu.ca/posts/ryan-air Using graph theory and Ryanair route data to find cheap multi-city flight loops through Europe. Fri, 23 Nov 2018 21:14:51 GMT https://jonlu.ca/posts/churning-primer https://jonlu.ca/posts/churning-primer An introduction to credit card rewards, sign-up bonuses, and the mechanics of churning. Sun, 11 Nov 2018 17:11:41 GMT https://jonlu.ca/posts/phone-calls https://jonlu.ca/posts/phone-calls Exploring bandwidth, filtering, and compression to reproduce the distinctive sound of phone calls. Mon, 29 Oct 2018 01:17:38 GMT https://jonlu.ca/posts/illegal-streams https://jonlu.ca/posts/illegal-streams Building a better sports stream viewer by extracting HLS playlists, keys, cookies, and headers. Sat, 22 Sep 2018 15:14:32 GMT https://jonlu.ca/posts/leaky-abstractions https://jonlu.ca/posts/leaky-abstractions Why every abstraction leaks, and why good abstractions give users a deliberate way through. Sat, 04 Aug 2018 18:07:47 GMT https://jonlu.ca/posts/the-federalist-papers-author-identification-through-k-means-clustering https://jonlu.ca/posts/the-federalist-papers-author-identification-through-k-means-clustering Using K-means clustering on writing style to classify disputed Federalist Papers authorship. Sun, 08 Jul 2018 02:06:19 GMT https://jonlu.ca/posts/the-rise-of-megathreads-on-reddit https://jonlu.ca/posts/the-rise-of-megathreads-on-reddit Lessons from moderating online communities about when megathreads help and when they hurt discussion. Thu, 07 Jun 2018 02:06:43 GMT https://jonlu.ca/posts/speeding-up-zsh https://jonlu.ca/posts/speeding-up-zsh Profiling shell startup and trimming Oh My Zsh and NVM overhead for a faster terminal. Wed, 16 May 2018 18:43:26 GMT https://jonlu.ca/posts/old-code-is-institutional-knowledge https://jonlu.ca/posts/old-code-is-institutional-knowledge Why maintaining old code creates institutional knowledge that clean rewrites can easily erase. Thu, 26 Apr 2018 14:55:06 GMT https://jonlu.ca/posts/on-uscs-csci-350-operating-systems https://jonlu.ca/posts/on-uscs-csci-350-operating-systems A student's reflection on USC's operating systems course, its workload, and what made it valuable. Tue, 24 Apr 2018 03:10:25 GMT https://jonlu.ca/posts/disambiguating-type-systems https://jonlu.ca/posts/disambiguating-type-systems Clarifying the difference between static, dynamic, strong, and weak type systems. Thu, 19 Apr 2018 18:18:17 GMT https://jonlu.ca/posts/information https://jonlu.ca/posts/information Thinking about information propagation, scale, and how the internet changed what people can know. Mon, 16 Apr 2018 16:52:00 GMT https://jonlu.ca/posts/wpm https://jonlu.ca/posts/wpm Why words per minute oversimplifies typing skill and ignores the work that actually slows programmers down. Sun, 15 Apr 2018 20:48:35 GMT https://jonlu.ca/posts/why-does-this-exist https://jonlu.ca/posts/why-does-this-exist Why this personal blog exists as a home for exploratory, opinionated, and loosely edited writing. Sun, 15 Apr 2018 19:00:00 GMT https://jonlu.ca/posts/optimizing-a-static-site https://jonlu.ca/posts/optimizing-a-static-site How compression, caching, HTTP/2, and deployment changes made a static personal site dramatically faster. Fri, 16 Mar 2018 19:00:00 GMT