http://localhost:3000A personal, searchable notebook of developer notes: frontend, backend, DevOps, blockchain, projects and interview prep.http://localhost:3000/notes/projects/brainlyhttp://localhost:3000/notes/projects/brainlySun, 28 Dec 2025 00:00:00 GMTBasic things to start a project Npm init -y Npm install -d typescript Npx tsc –init Change the comments in the file for src and out directory and create index.ts file inside the src folder for express add this too in the tsconfig file upper one is the new synhttp://localhost:3000/notes/devops/dockerhttp://localhost:3000/notes/devops/dockerFri, 03 Apr 2026 00:00:00 GMTDOCKER CONTAINER === ITS LIKE A SMALL MACHINE LIKE A VM WE CAN SAY ONE USECASE IS THIS LIKE WHEN YOUR FRIEND SOMETHING SEND YOU SUS AND YOU WANT TO TRY WHAT IS THAT RUN IT INSIDE THE DOCKER CONTAINER THEY ALSO HAVE THERE OWN FILESYSTEM Docker/containers are imhttp://localhost:3000/notes/blockchain/history-of-blockchainhttp://localhost:3000/notes/blockchain/history-of-blockchainMon, 18 May 2026 00:00:00 GMTTimeline THE BIG SHORT MOVIE 2008 - Global Financial Crisis. 2009 - Bitcoin whitepaper <https://bitcoin.org/bitcoin.pdf> 2010 - The 10k BTC Pizza <https://www.youtube.com/watch?v=j28hkTJMuTA> 2015 – Ethereum Launch 2018 – Solana Founded 2020 – Solana Mainnet Bhttp://localhost:3000/notes/backend/ts-project-inithttp://localhost:3000/notes/backend/ts-project-initTue, 17 Feb 2026 00:00:00 GMTHow to intiliaze a ts project? Create a folder using terminal use mkdir Then use pwd to access the path Then in vscode open it using the open folder option npm init –y (initialize a empty package.json) npm install typescript npx tsc –init (initialize a tsconfihttp://localhost:3000/notes/interview/interview-questionshttp://localhost:3000/notes/interview/interview-questionsMon, 30 Mar 2026 00:00:00 GMTWhat is useeffect hook? What is react lifecycle? Introduce yourself on what project you are currently working onhttp://localhost:3000/notes/frontend/javascripthttp://localhost:3000/notes/frontend/javascriptWed, 04 Mar 2026 00:00:00 GMTJavaScript (PDF) These notes are kept as a PDF. Use the embedded viewer below, or download the PDF.http://localhost:3000/notes/devops/kubernetes-1http://localhost:3000/notes/devops/kubernetes-1Sun, 24 May 2026 00:00:00 GMTWhat is kubernetes Docker is a pre-requisite before you proceed to understand kubernetes Kubernetes (popularly known as k8s) is a container orchestration engine, which as the name suggests lets you create, delete, and update containers This is useful when Youhttp://localhost:3000/notes/projects/medium-bloghttp://localhost:3000/notes/projects/medium-blogMon, 13 Apr 2026 00:00:00 GMTFOR BACKEND WE ARE USING HONO INSTEAD OF EXPRESS BECAUSE THE ISSUE IS HONO WORKS BETTER WITH CLOUDWORKS SO THATS WHY Hono is built for serverless functions creating be folder and for installing hono using this npm create <hono@latest> creating the endpoints Tohttp://localhost:3000/notes/backend/postgreshttp://localhost:3000/notes/backend/postgresThu, 19 Feb 2026 00:00:00 GMTTo identify who is using mongodb, firebase Go to api calls and see the id field if the id field contains __id: after this there is a object id then See the eg Mongo db has horizontal scaling POSTGRESS WE HAVE TO REALLY GOOD AT MONGO DB is a no sql databases ,http://localhost:3000/notes/blockchain/public-key-cryptographyhttp://localhost:3000/notes/blockchain/public-key-cryptographyMon, 18 May 2026 00:00:00 GMTIn US as you login you can just pay you don’t have to give any otp Some websites like coindcx, wazirx, coinbase, backpack exchange etc Metamask wallet Famous phrase NOT YOUR KEYS NOT YOUR CRYPTO LOL How banks do Auth In traditional banks, you have a username ahttp://localhost:3000/notes/frontend/typescripthttp://localhost:3000/notes/frontend/typescriptWed, 24 Dec 2025 00:00:00 GMT Javascript is a loosely typed language to make it strongly so that the errors in the code can be solved in compile only for that the devs made TYPESCRIPT it just js but with types Step to create a ts project: npm install -g typescript ( to globally installhttp://localhost:3000/notes/blockchain/hd-wallets-dappshttp://localhost:3000/notes/blockchain/hd-wallets-dappsMon, 18 May 2026 00:00:00 GMTEARLIER WHAT WAS THE ISSUE WAS YOU HAVE TO KEEP PUBLIC AND PRIVATE KEYS FOR ALL THE WALLETS WHICH WERE KNOWN AS HD WALLETS FOR THAT WE HAVE TO REMEMBER SO MANY CODES Hierarchical Deterministic (HD) Wallet Hierarchical Deterministic (HD) wallets are a type of whttp://localhost:3000/notes/devops/kubernetes-2http://localhost:3000/notes/devops/kubernetes-2Wed, 27 May 2026 00:00:00 GMT Currently trying to do everything from the first principle for understanding but mainly we will be using the ingress, certmanager.io these things only in the production you can also use civo.com for the k8s cluster WHAT IS NAMESPACE? It just helps to create ahttp://localhost:3000/notes/projects/paytmhttp://localhost:3000/notes/projects/paytmSat, 28 Mar 2026 00:00:00 GMTFirst using the docker file first off check in the docker folder or not docker build ./ -t mongodb:4.7-replset then to run it use docker run mongodb:4.7-replset docker run -d -p 27017:27017 mongodb:4.7-replset use this one to run at a specific port docker run http://localhost:3000/notes/backend/prismahttp://localhost:3000/notes/backend/prismaMon, 13 Apr 2026 00:00:00 GMTCloudfare for servers or Amazon dynamodb they do everything themselves scales well and expensive also Firebase also good ORMS (Object Relational Mapping) 1. Boring official defination ORM stands for Object-Relational Mapping, a programming technique used in sohttp://localhost:3000/notes/frontend/reacthttp://localhost:3000/notes/frontend/reactWed, 04 Mar 2026 00:00:00 GMTReact (PDF) These notes are kept as a PDF. Use the embedded viewer below, or download the PDF.http://localhost:3000/notes/devops/kubernetes-3http://localhost:3000/notes/devops/kubernetes-3Fri, 29 May 2026 00:00:00 GMT­SCALING OF THE K8S(LAST UHUHUHUHUHU) HORIZONTAL POD AUTOSCALER Ref - <https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/> A Horizontal Pod Autoscaler (HPA) is a Kubernetes feature that automatically adjusts the number of pod replicas ihttp://localhost:3000/notes/backend/monorepo-turborepohttp://localhost:3000/notes/backend/monorepo-turborepoFri, 06 Mar 2026 00:00:00 GMTSearch for dubinc/dub there the monorepo concept is used Its like weired way of structuring the project What are monorepos As the name suggests, a single repository (on github lets say) that holds all your frontend, backend, devops code. Few repos that use monhttp://localhost:3000/notes/frontend/nextjshttp://localhost:3000/notes/frontend/nextjsTue, 24 Feb 2026 00:00:00 GMTRemix / Next js Next js contains both frontend and backend for a project as like the react only has frontend NextJS was a framework that was introduced because of some minor inconviniences in React 1. In a React project, you have to maintain a separate Backendhttp://localhost:3000/notes/blockchain/solana-jargonhttp://localhost:3000/notes/blockchain/solana-jargonWed, 13 May 2026 00:00:00 GMTSolana is the one which introduced the smart contracts Context?? Why eth and sol are better than solana? When bitcoin came it just solved one usecase which was the decentralized currency during that time only many of the people started creating there own bitcohttp://localhost:3000/notes/projects/trellohttp://localhost:3000/notes/projects/trelloSun, 17 May 2026 00:00:00 GMT Above is the whole structure of the project General flow for creating a application 1. Design your db schema 2. Create your backend 3. Tests for backend 4. Frontend ALWAYS REMEMBER TO MAINTAIN ID FOR ALL THE USERS LIKE IN DB WE DO THAT SO THIS ALSO TRY TO MAIhttp://localhost:3000/notes/devops/aws-cert-managementhttp://localhost:3000/notes/devops/aws-cert-managementThu, 07 May 2026 00:00:00 GMT Domains vs IPs localhost "Localhost" refers to the computer you're currently working on. It's essentially a loopback address that points to the machine itself, allowing it to communicate with itself over a network. In technical terms, the IP address for localhttp://localhost:3000/notes/frontend/tailwindhttp://localhost:3000/notes/frontend/tailwindFri, 12 Dec 2025 00:00:00 GMTThings to know in a frontend framework Flex, Grids, Responsiveness, background color, hover Without flex With flex Refer slides for more Writing the same thing in short method us ts Grids: Responsiveness In this the one with no prefix is the default one and http://localhost:3000/notes/blockchain/token-launchpadhttp://localhost:3000/notes/blockchain/token-launchpadThu, 14 May 2026 00:00:00 GMTACTUAL THING WHAT WE ARE BUILDING? Transactions vs instructions When you send a transaction to the solana blockchain, you are actually sending a bunch of instructions (with a limit to the max number of instructions you can send) instructions is like what arehttp://localhost:3000/notes/backend/week-10http://localhost:3000/notes/backend/week-10Sat, 06 Dec 2025 00:00:00 GMTSingle page loader When we use to switch from one page to another in earlier time(html,css,js) there is a refresh loader in the top. SPL is like when you are not switching the whole page just some content is changing and the top bar remains the same. You are chttp://localhost:3000/notes/projects/zapierhttp://localhost:3000/notes/projects/zapierThu, 09 Apr 2026 00:00:00 GMTUse of zapier razorpay = payment gateway usecase of zapier like when you do buy a course there are many options imagine we bought service from appx and they just provide payment in inr so the issue is we want in usd also how we will do? To fix that we like crhttp://localhost:3000/notes/devops/aws-ecr-ecshttp://localhost:3000/notes/devops/aws-ecr-ecsFri, 15 May 2026 00:00:00 GMTThis is like amazon answer to kubernetes if you want similar benefits like kubernetes in aws use this ECS = Elastic container service(Container orchestrator) kubernetes is also a container orchestrator ECS is more easier that kubernetes ECS downside is it can http://localhost:3000/notes/frontend/ui-uxhttp://localhost:3000/notes/frontend/ui-uxTue, 09 Dec 2025 00:00:00 GMTTypeface – Poppins in a type face and fonts inside that are the part of the poppins family Line Height - 150 for heading, 120 for body text Letter Spacing – 0 - -3 % typescale.com - for checking how the website looks with certain fonts fontshare.com – cool fonhttp://localhost:3000/notes/devops/ci-cd-vmshttp://localhost:3000/notes/devops/ci-cd-vmsSun, 05 Apr 2026 00:00:00 GMTnpm install -g bun npx <create-turbo@latest> create db folder in the packages folder bun init cd packages mkdir db cd db bun init bun install prisma bunx prisma init bun add dotenv defining the schema model User { id String @id @default(uuid()) username Stringhttp://localhost:3000/notes/frontend/websocketshttp://localhost:3000/notes/frontend/websocketsMon, 16 Feb 2026 00:00:00 GMTSocketIO is used by Canva and razerpay Websocket protocol is like http only WebSockets provide a way to establish a persistent, full-duplex communication channel over a single TCP connection between the client (typically a web browser) and the server. Persistehttp://localhost:3000/notes/devops/serverlesshttp://localhost:3000/notes/devops/serverlessWed, 20 May 2026 00:00:00 GMT­WHAT ARE BACKEND SERVERS? They are like simple servers used in startups, hackathons etc initially its good but for scale its expensive so not used for scale Vercel, Render are all serverless and good to use WHAT IS SERVERLESS BACKENDS? The better method to dhttp://localhost:3000/notes/devops/scaling-and-indexeshttp://localhost:3000/notes/devops/scaling-and-indexesSun, 12 Apr 2026 00:00:00 GMTIf the usage is increased in the db so we can do like buy a bigger machine and then use that but this does not matter in js because its a single threaded language something off topic like imagine you have 16 cores and 16 application running it does not mean thhttp://localhost:3000/notes/devops/process-managementhttp://localhost:3000/notes/devops/process-managementFri, 06 Mar 2026 00:00:00 GMT TO TAKE ACCESS: we first check the name of the user using whoami icacls "D:\Data\Save\Keys\pallab-key-pari.pem" /grant desktop-abc123\pallab:F icacls "D:\Data\Save\Keys\pallab-key-pari.pem" /remove "BUILTIN\Users" icacls "D:\Data\Save\Keys\pallab-key-pari.pemhttp://localhost:3000/notes/devops/monitoring-newrelichttp://localhost:3000/notes/devops/monitoring-newrelicFri, 15 May 2026 00:00:00 GMTPAGER DUTY, BETTER UP TIME USED FOR MONITORING Logging, monitoring, alerts and status pages Logging Logging refers to the practice of recording events, messages, or data points generated by software applications and systems. These logs can include various typehttp://localhost:3000/notes/devops/self-hosted-monitoringhttp://localhost:3000/notes/devops/self-hosted-monitoringSun, 17 May 2026 00:00:00 GMTPrometheus and Grafana (Open source monitoring tools) DATADOG AND NEWRELIC PAID ONES for this we have to learn prometheus query language Revise monitoring In the last live, we understood what is monitoring. We created dashboards that looked like the following http://localhost:3000/notes/devops/autoscaling-orchestratorhttp://localhost:3000/notes/devops/autoscaling-orchestratorWed, 13 May 2026 00:00:00 GMTLike in the bolt and online application creator website whenever we write a application like chess app it starts to create the application on a vscode terminal on the side how that is done? Its like whenever a request is made that pumps up a machine in which a