Come for the code, stay for the cats.https://danlevy.net/https://danlevy.net/open-source-journal/https://danlevy.net/open-source-journal/A collection of open-source projects I've worked on.Mon, 16 Dec 2024 00:00:00 GMTProjectsopen-sourceprojectshttps://danlevy.net/into-the-breach/https://danlevy.net/into-the-breach/Prevent AI powered attacks with decoys & subterfugeWed, 13 May 2026 00:00:00 GMTSecuritysecuritydeveloper-experienceinfostealerscredentialsdevcontainerssupply-chainai-agentscanary-tokensprompt-injectiongithub-actionsci-cdhttps://danlevy.net/postgres-text-search-guide/https://danlevy.net/postgres-text-search-guide/The search tools already in your database, and when each one earns its keep.Sat, 02 May 2026 00:00:00 GMTCodepostgrespostgresqlfull-text-searchtrigramspg_trgmdatabasessearchsqlpg_searchhttps://danlevy.net/llm-evals-are-broken/https://danlevy.net/llm-evals-are-broken/Benchmarks measure benchmarks. Your system needs its own measures.Fri, 01 May 2026 00:00:00 GMTAIaillmevalstestingproductionqualityobservabilityhttps://danlevy.net/semantic-vector-search-landscape/https://danlevy.net/semantic-vector-search-landscape/The full search landscape: exact, fuzzy, semantic, hybrid — and when to layer all of them.Fri, 01 May 2026 00:00:00 GMTCodepostgrespostgresqlpgvectorvector-searchsemantic-searchhybrid-searchragaidatabasessearchembeddingshttps://danlevy.net/llm-connection-strings/https://danlevy.net/llm-connection-strings/Simplify Model & Provider Config with `llm://` URLsFri, 30 Jan 2026 00:00:00 GMTAIaillmapideveloper-experiencestandardshttps://danlevy.net/securing-clawdbot-tailscale/https://danlevy.net/securing-clawdbot-tailscale/How to secure your local or VPS OpenClaw/Moltbot setupThu, 15 Jan 2026 00:00:00 GMTSecuritysecuritymoltbotclawdbottailscaleaivpndevopssshhttps://danlevy.net/ai-sdk-math-tool/https://danlevy.net/ai-sdk-math-tool/They are bad at it. Here is how to fix it.Tue, 06 Jan 2026 00:00:00 GMTAIaiai-sdktypescriptmathtoolspatternshttps://danlevy.net/mastra-workflows-memory/https://danlevy.net/mastra-workflows-memory/Deterministic patterns for non-deterministic models.Mon, 05 Jan 2026 00:00:00 GMTAIaiworkflowsmemorymastraagent-networksorchestrationhttps://danlevy.net/mastra-mcp-tool-integrations/https://danlevy.net/mastra-mcp-tool-integrations/Why MCP is the USB-C of Artificial Intelligence.Sun, 04 Jan 2026 00:00:00 GMTAIaimcptoolsintegrationsmastrasalesforceapishttps://danlevy.net/mastra-security-guardrails/https://danlevy.net/mastra-security-guardrails/If your agent doesn't have guardrails, you aren't ready for production.Sat, 03 Jan 2026 00:00:00 GMTAIaisecuritymastraguardrailsprivacypiihttps://danlevy.net/llm-routing-mastra-ai/https://danlevy.net/llm-routing-mastra-ai/LLM Routing, so hot right nowFri, 02 Jan 2026 00:00:00 GMTAIaillmtypescriptmastraagent-orchestrationhttps://danlevy.net/your-foreign-keys-are-killing-performance/https://danlevy.net/your-foreign-keys-are-killing-performance/Ask what you're actually optimizing for.Mon, 29 Dec 2025 00:00:00 GMTCodepostgrespostgresqldatabasesperformanceforeign-keysconstraintsindexinghttps://danlevy.net/weakmap-the-javascript-feature-you-dont-use/https://danlevy.net/weakmap-the-javascript-feature-you-dont-use/Fixing weak code with weak references!Mon, 29 Dec 2025 00:00:00 GMTCodejavascriptmemorygarbage-collectionperformancepatternshttps://danlevy.net/the-jsonb-seduction/https://danlevy.net/the-jsonb-seduction/JSONB is powerful, useful, and very easy to misuse when you let a blob become your real schema.Mon, 29 Dec 2025 00:00:00 GMTCodepostgrespostgresqldatabasesjsonbjsonschema-designtechnical-debthttps://danlevy.net/the-8-byte-timestamp-that-destroyed-our-database/https://danlevy.net/the-8-byte-timestamp-that-destroyed-our-database/What a train ticket taught me about storing time in databasesMon, 29 Dec 2025 00:00:00 GMTCodepostgrespostgresqldatabasestimestampstimezonesmicroservicesdebugginghttps://danlevy.net/async-stack-traces-why-error-stack-lies-in-production/https://danlevy.net/async-stack-traces-why-error-stack-lies-in-production/The microtask queue ate my homework (and my debugging context).Mon, 29 Dec 2025 00:00:00 GMTCodejavascriptasyncdebuggingnode.jsv8performancehttps://danlevy.net/quiz-advanced-js-error-mastery/https://danlevy.net/quiz-advanced-js-error-mastery/Are your exceptions truly exceptional?Mon, 03 Nov 2025 00:00:00 GMTQuizquizjavascripterror-handlingdebuggingadvancedhttps://danlevy.net/serverless-database-magic/https://danlevy.net/serverless-database-magic/You can thank AI.Wed, 10 Sep 2025 00:00:00 GMTSearchserverlessdatabasesaiinnovationchromalancedbpagefindoramaduckdbhttps://danlevy.net/patchy-with-a-chance-of-vulnerability/https://danlevy.net/patchy-with-a-chance-of-vulnerability/Why updates can't save youWed, 10 Sep 2025 00:00:00 GMTSecuritysecuritypatchessoftware-updatesrisk-managemententerprise-ithttps://danlevy.net/the-last-to-think/https://danlevy.net/the-last-to-think/Human or Machine?Sat, 31 May 2025 00:00:00 GMTAIedtecheducationtechnologyhistoryhttps://danlevy.net/beware-the-single-purpose-people/https://danlevy.net/beware-the-single-purpose-people/So pure it hurtsMon, 14 Apr 2025 00:00:00 GMTCodesoftware-developmentcode-organizationmaintainabilitytestingdogmapragmatismhttps://danlevy.net/you-might-not-need-algolia/https://danlevy.net/you-might-not-need-algolia/Static sites probably do not need hosted searchSat, 01 Mar 2025 00:00:00 GMTSearchsearchalgoliapagefindcdnhttps://danlevy.net/docker-security-tips-for-self-hosting/https://danlevy.net/docker-security-tips-for-self-hosting/Secure your self-hosted services, from defense to monitoring!Sat, 04 Jan 2025 00:00:00 GMTSecuritydockersecuritydevopscontainersbest-practiceshttps://danlevy.net/the-unassuming-power-of-multiple-choice-questions/https://danlevy.net/the-unassuming-power-of-multiple-choice-questions/How to Harness the Full Potential of MCQs in EducationWed, 01 Jan 2025 00:00:00 GMTInstructional Designeducationassessmentlearningmultiple-choice-questionshttps://danlevy.net/from-zero-to-regex-hero-extract-url-like-strings/https://danlevy.net/from-zero-to-regex-hero-extract-url-like-strings/Extract & Parse URL-like Strings with a Single RegexSun, 29 Dec 2024 00:00:00 GMTRegexregexurldata-extractiondata-processinghttps://danlevy.net/quiz-is-your-memory-rusty/https://danlevy.net/quiz-is-your-memory-rusty/(Borrow) check yo self before you wreck yo self! 🦀Sat, 28 Dec 2024 00:00:00 GMTQuizquizrustmemory-managementownershipborrowinglifetimesintermediateadvancedhttps://danlevy.net/quiz-in-the-aws-cloud/https://danlevy.net/quiz-in-the-aws-cloud/Can you navigate the cloud labyrinth?Sat, 28 Dec 2024 00:00:00 GMTQuizquizawscloudstoragedatabasess3dynamodbrdselasticachehttps://danlevy.net/replacing-my-job-with-gpt-and-llm/https://danlevy.net/replacing-my-job-with-gpt-and-llm/How I learned to stop worrying and love the GPT.Wed, 04 Dec 2024 00:00:00 GMTAIaigptllmmachine-learningnlpautomationhttps://danlevy.net/quiz-postgres-sql-mastery-pt2/https://danlevy.net/quiz-postgres-sql-mastery-pt2/Are you SQL Steele? Or a SQL Softie?Thu, 28 Nov 2024 00:00:00 GMTQuizquizpostgresqlsqldatabaseintermediateadvancedhttps://danlevy.net/quiz-postgres-sql-mastery-pt1/https://danlevy.net/quiz-postgres-sql-mastery-pt1/Does SQL make you squeal?Wed, 27 Nov 2024 00:00:00 GMTQuizquizpostgresqlsqldatabaseintermediateadvancedhttps://danlevy.net/quiz-bash-in-the-shell/https://danlevy.net/quiz-bash-in-the-shell/Can you talk to computers? Like, well?Wed, 20 Nov 2024 00:00:00 GMTQuizquizbashscriptingshelllinuxbeginnerintermediateadvancedhttps://danlevy.net/quiz-regex-or-wreckage/https://danlevy.net/quiz-regex-or-wreckage/Can you tame some wild RegEx?Fri, 15 Nov 2024 00:00:00 GMTQuizquizregexjavascriptintermediatepatternshttps://danlevy.net/quiz-nodejs-files-streams-buffers-oh-my/https://danlevy.net/quiz-nodejs-files-streams-buffers-oh-my/Test your knowledge of files, streams & buffersFri, 15 Nov 2024 00:00:00 GMTQuizquiznodejsiostreamsbuffersfilesystemintermediatehttps://danlevy.net/quiz-destructuring-delights/https://danlevy.net/quiz-destructuring-delights/Are you a maestro of Destructuring?Tue, 12 Nov 2024 00:00:00 GMTQuizquizintrojavascriptes2015destructuringbeginnerintermediatehttps://danlevy.net/quiz-sql-query-fundamentals/https://danlevy.net/quiz-sql-query-fundamentals/Are you team SQL? Or noSQL?Fri, 08 Nov 2024 00:00:00 GMTQuizquizintrosqlcorefundamentalsbeginnerintermediatehttps://danlevy.net/quiz-css-core-fundamentals/https://danlevy.net/quiz-css-core-fundamentals/Are you front-end enough?Fri, 08 Nov 2024 00:00:00 GMTQuizquizintrocssstylesbeginnerintermediatehttps://danlevy.net/quiz-modern-css-2025/https://danlevy.net/quiz-modern-css-2025/Are you front-end enough?Thu, 31 Oct 2024 00:00:00 GMTQuizquizcssadvancedintermediatehttps://danlevy.net/quiz-can-you-count-to-bigint/https://danlevy.net/quiz-can-you-count-to-bigint/Know your `parseInt` from `parseFloat`?Thu, 31 Oct 2024 00:00:00 GMTQuizquizdata-structuresalgorithmshttps://danlevy.net/quiz-master-modern-html5/https://danlevy.net/quiz-master-modern-html5/Prove yourself!Thu, 31 Oct 2024 00:00:00 GMTQuizquizwebquizsemantichtml5webbeginnerintermediatehttps://danlevy.net/quiz-js-interfaces-symbols-and-enumerables/https://danlevy.net/quiz-js-interfaces-symbols-and-enumerables/Do you know the less-famous bits of ES2015?Thu, 31 Oct 2024 00:00:00 GMTQuizquizjavascriptinterfacessymbolsenumerableshttps://danlevy.net/quiz-do-you-know-esnext/https://danlevy.net/quiz-do-you-know-esnext/Prove your esteemed JavaScript skillz!Thu, 31 Oct 2024 00:00:00 GMTQuizquizjavascriptintroesnextfeaturesintermediatehttps://danlevy.net/quiz-data-structures-algorithms/https://danlevy.net/quiz-data-structures-algorithms/Can you BS a Binary Tree?Thu, 31 Oct 2024 00:00:00 GMTQuizquizdata-structuresalgorithmsintermediateadvancedhttps://danlevy.net/honest-priorities/https://danlevy.net/honest-priorities/Is Multiple Choice the Best Choice?Wed, 23 Oct 2024 00:00:00 GMTThoughtsagileleadershipprioritybacklogjirahttps://danlevy.net/one-weird-trick-to-speed-up-feature-teams/https://danlevy.net/one-weird-trick-to-speed-up-feature-teams/Staff engineers hate this!Sun, 29 Sep 2024 00:00:00 GMTEngineeringagileteamshttps://danlevy.net/breaking-unicorns/https://danlevy.net/breaking-unicorns/Breaking UnicornsWed, 25 Sep 2024 00:00:00 GMTLulzbreaking-unicornsstartupsatiresilicon-valleyhttps://danlevy.net/handling-international-numbers-and-currency/https://danlevy.net/handling-international-numbers-and-currency/Localized money explained!Wed, 28 Aug 2024 00:00:00 GMTHowToengineeringinternationalizationlocalizationcurrencynumbershttps://danlevy.net/upgrade-from-gatsby-to-astro/https://danlevy.net/upgrade-from-gatsby-to-astro/Astro, Tailwind, MDX, Pagefind, and more!Wed, 21 Aug 2024 00:00:00 GMTGuidesastrotailwindmdxpagefindgatsbyhttps://danlevy.net/contribute-to-open-source-the-easy-way/https://danlevy.net/contribute-to-open-source-the-easy-way/In 3 Simple Steps...Tue, 16 Jan 2024 00:00:00 GMTGuidesengineeringopen-sourceosshttps://danlevy.net/guerrilla-types-in-typescript/https://danlevy.net/guerrilla-types-in-typescript/Renegade Type DesignTue, 05 Sep 2023 00:00:00 GMTGuidesengineeringtypescriptcompositiontypeshttps://danlevy.net/deathmatch-git-rebase-vs-merge/https://danlevy.net/deathmatch-git-rebase-vs-merge/A timeless question...Sun, 27 Aug 2023 00:00:00 GMTThoughtsengineeringgitrebasemergehttps://danlevy.net/should-you-use-named-or-default-exports/https://danlevy.net/should-you-use-named-or-default-exports/To name, or not to name?Thu, 10 Aug 2023 00:00:00 GMTGuidestypescriptjavascriptmoduleshttps://danlevy.net/mastering-functional-pipelines-passing-state/https://danlevy.net/mastering-functional-pipelines-passing-state/Hello Closure, My Old Friend.Wed, 09 Aug 2023 00:00:00 GMTGuidestypescriptclosurestatefulscopinghoistingfunctionalpipelinehttps://danlevy.net/the-4-pillars-of-collaborative-culture/https://danlevy.net/the-4-pillars-of-collaborative-culture/Safety, Speed, Clarity and Commitment.Sat, 03 Apr 2021 00:00:00 GMTLeadershipcollaborative-culturecultureteamsgrowthpersonal-developmenthttps://danlevy.net/creating-collaborative-culture/https://danlevy.net/creating-collaborative-culture/Unlock your teams' creativity!Fri, 01 Jan 2021 00:00:00 GMTLeadershipcollaborative-culturecultureteamsgrowthpersonal-developmenthttps://danlevy.net/js-quiz-14-date-time-questions-test-your-knowledge/https://danlevy.net/js-quiz-14-date-time-questions-test-your-knowledge/Learn to impress at parties with JS trivia! ✨Thu, 02 Jan 2020 00:00:00 GMTQuizquizjavascriptdatedategotchaschallengeintermediatehttps://danlevy.net/javascript-promises-quiz/https://danlevy.net/javascript-promises-quiz/Never drop a promise again!Tue, 26 Nov 2019 00:00:00 GMTQuizpromisesprogrammingasyncjavascriptguidesquizintermediatehttps://danlevy.net/you-may-not-need-axios/https://danlevy.net/you-may-not-need-axios/Fetch API to the rescue!Wed, 14 Nov 2018 00:00:00 GMTGuidesprogrammingpatternsexamplesnodejsjavascriptpromisesaxiosfetchhttps://danlevy.net/securely-using-environment-variables-in-nodejs/https://danlevy.net/securely-using-environment-variables-in-nodejs/Using `dotenv`Tue, 13 Nov 2018 00:00:00 GMTCodedotenvapi-keyssecretstokenssecuritynodejshttps://danlevy.net/protect-your-tokens/https://danlevy.net/protect-your-tokens/Public? Private? Wat?Sat, 27 Oct 2018 00:00:00 GMTGuidestokensapi-keyssecretssecuritynodejsjson-web-tokenshttps://danlevy.net/are-promises-broken/https://danlevy.net/are-promises-broken/Dropping errors, losing results...Sat, 06 Oct 2018 00:00:00 GMTCodepromisesjavascripterrorsprogramminghttps://danlevy.net/stop-trying-to-make-async-await-happen/https://danlevy.net/stop-trying-to-make-async-await-happen/Promises are so fetch right nowWed, 03 Oct 2018 00:00:00 GMTGuidespromisesasyncawaitasync-awaitjavascriptcompositionhttps://danlevy.net/visualizing-promises/https://danlevy.net/visualizing-promises/Break on through...Sun, 30 Sep 2018 00:00:00 GMTGuidespromisesasyncvisualizingjavascriptcompositionhttps://danlevy.net/promise-gotchas/https://danlevy.net/promise-gotchas/Avoiding common mistakesWed, 26 Sep 2018 00:00:00 GMTCodepromisesasyncdebuggingerrorsjavascriptcompositionhttps://danlevy.net/intro-to-promises/https://danlevy.net/intro-to-promises/JavaScript Promises Are Fun!Wed, 01 Aug 2018 00:00:00 GMTCodepromisesasyncjavascriptcompositionhttps://danlevy.net/pitfalls-in-promise-docs/https://danlevy.net/pitfalls-in-promise-docs/Avoiding issues from popular docsWed, 10 May 2017 00:00:00 GMTCodeprogrammingpatternspromisesfunctional-programminghttps://danlevy.net/compare-nvme-ssd-cloud-options/https://danlevy.net/compare-nvme-ssd-cloud-options/NVMe SSD Head-to-Head: AWS, DigitalOcean, Packet.netSat, 15 Apr 2017 00:00:00 GMTDevOpscloudserversarchitecturescalingdigital-oceanamazon-web-servicesgoogle-cloud-engineazurepacketovhssdiohttps://danlevy.net/naming-things-real-good/https://danlevy.net/naming-things-real-good/Naming stuff: Object Oriented BasicsWed, 01 Jun 2016 00:00:00 GMTGuidesprogrammingpatternsnamingsource-codeorganizationhttps://danlevy.net/when-ai-fails-and-the-crashing-robot-cars/https://danlevy.net/when-ai-fails-and-the-crashing-robot-cars/Google's self-driving cars are in 2x as many accidents as human driversFri, 18 Dec 2015 00:00:00 GMTAIartificial-intelligenceaiself-driving-carsfailshttps://danlevy.net/higher-order-programming/https://danlevy.net/higher-order-programming/Exploring Array- and Set-based Pipeline TechniquesTue, 22 Sep 2015 00:00:00 GMTCodeprogrammingpatternsmodelssource-codeorganizationhttps://danlevy.net/angularjs-v2-impending-schism/https://danlevy.net/angularjs-v2-impending-schism/Can it be avoided?Wed, 05 Aug 2015 00:00:00 GMTThoughtsprogrammingangularjsjavascriptpythonopinionhttps://danlevy.net/docker-rocks/https://danlevy.net/docker-rocks/Docker is amazing, fast, and flexibleThu, 11 Jun 2015 00:00:00 GMTDevOpsdockerboot2dockerdevopshttps://danlevy.net/docker-server-setup-notes/https://danlevy.net/docker-server-setup-notes/Start Database Servers w/ single commandsMon, 06 Apr 2015 00:00:00 GMTDevOpsdevopsdockerserverpostgresmysqlmongodbelasticsearchsetupshell-scripthttps://danlevy.net/docker-makes-everything-better/https://danlevy.net/docker-makes-everything-better/Docker can do :allthethings:!Thu, 26 Feb 2015 00:00:00 GMTDevOpsdockerdevopspatternshttps://danlevy.net/stop-the-angularjs-hate/https://danlevy.net/stop-the-angularjs-hate/AngularJS CAN BE Fun!Thu, 26 Feb 2015 00:00:00 GMTCodeangularjsdevelopmentperformanceprogramminghttps://danlevy.net/amazing-resources/https://danlevy.net/amazing-resources/A curated 2026 list of UI kits, Tailwind blocks, icons, fonts, illustrations, animations, and design tools for building polished websites faster.Thu, 26 Feb 2015 00:00:00 GMTCodedevelopmentdesignresourcesuitailwindiconspatternshttps://danlevy.net/security-notes-regex/https://danlevy.net/security-notes-regex/Can RegEx be vulnerable?Tue, 24 Feb 2015 00:00:00 GMTSecuritysecurityregexdosremote-exploit