What rclone can mount an S3 bucket as a Windows drive letter, making it appear in File Explorer like a local drive. This guide covers configuring one S3 remote, writing a mount batch file, and optionally starting it at sign-in. You need an AWS account with an S3 bucket and IAM user, rclone for Windows, and WinFSP installed (required for rclone mount on Windows). Why Faster access: Browse S3 in File Explorer without separate apps or consoles. Simplicity: Open, copy, rename like a normal drive letter. Integrations: Any Windows app that works with drive letters can work with S3. How Step 1: Install rclone + WinFSP ...

What Two paths: controller exceptions vs pre-controller (filters/interceptors) exceptions. Single response shape via GlobalExceptionHandler for both paths. Flow (who catches what): Controller throws → handled by @ControllerAdvice methods. Filter/interceptor throws → not handled by @ControllerAdvice unless you forward via HandlerExceptionResolver. Why Consistency: avoid container default error pages/messages. Control: send structured GenericResponse with proper HTTP codes. How Global handler (GlobalExceptionHandler): @ControllerAdvice class GlobalExceptionHandler { @ExceptionHandler(UnAuthorizedExceptionThrowable::class) fun handleUnauthorized(ex: UnAuthorizedExceptionThrowable, req: WebRequest): ResponseEntity<GenericResponse<Nothing>> { val body = GenericResponse<Nothing>( responseType = ResponseType.FAIL, message = ex.errorMessage, code = ex.code, type = ex.errorMessage ) return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body(body) } @ExceptionHandler(Exception::class) fun handleGeneric(ex: Exception, req: WebRequest) = ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body( GenericResponse<Nothing>( responseType = ResponseType.ERROR, message = ex.message ?: "Internal server error", code = HttpStatus.INTERNAL_SERVER_ERROR.value(), type = "Internal server error" ) ) } Explanation: ...

What FolderSync is an Android app that syncs local folders to S3-compatible storage. This guide sets up a private S3 bucket with a scoped IAM user and maps it to your device’s camera folder for automatic, private photo backup. You need an AWS account to start. Why Own your data: No Big Tech gallery lock-in. Reliability: S3 durability + Intelligent-Tiering for cost control. Simplicity: No self-hosted NAS, static IP, RAID, or server maintenance. How Step 1: Create S3 bucket (Region: us-east-1 recommended) ...

What CORS blocks non-whitelisted origins in AppSecurityConfig. JWT is validated for protected endpoints in JwtAuthenticationFilter using AuthenticationManagerJWT. API tiers restrict access even with a valid token; higher tiers grant access to more endpoints. Flow (request lifecycle): Incoming request → CORS applied → non-whitelisted origins blocked. Public/No-Auth endpoints bypass JWT checks. Protected endpoints → JWT extracted and validated. Tier authorization matched against requested API tier. On success, controller executes; on failure, error is routed to global handler. Why Prevent misuse from unwanted domains via strict CORS. Reject bad tokens: expired, blocked, reused/refresh-misuse. Enforce progression: open → tier 4 → tier 3 → tier 2 → tier 1 as business rules demand. How CORS configuration (AppSecurityConfig.corsConfigurationSource()): @Bean fun corsConfigurationSource(): CorsConfigurationSource { val configuration = CorsConfiguration() configuration.allowedOrigins = listOf( "http://localhost:3000", "https://yourdomain.com" ) configuration.allowedMethods = listOf("GET","POST","PUT","DELETE","OPTIONS","PATCH") configuration.allowedHeaders = listOf( "Authorization","Content-Type","X-Requested-With","Accept","Origin", KeywordsAndConstants.HEADER_TRACKING_ID, KeywordsAndConstants.HEADER_API_KEY, KeywordsAndConstants.HEADER_OTP, KeywordsAndConstants.HEADER_AUTH_TOKEN ) configuration.allowCredentials = true configuration.exposedHeaders = listOf( KeywordsAndConstants.HEADER_TRACKING_ID, KeywordsAndConstants.HEADER_API_TIER ) val source = UrlBasedCorsConfigurationSource() source.registerCorsConfiguration("/**", configuration) return source } Explanation: ...

Series links: Part 1/5 - Introduction Part 2/5 - Database Planning Part 3/5 - AWS Setup Part 4/5 - Backend APIs Part 5/5 - Frontend (you are here) What A small, fast web app that helps you add transactions with bills and later search/export them. Why Quick to use on phone or laptop. No heavy frameworks needed; it’s plain HTML/CSS/JS so you can host it anywhere. How Get the code Frontend source: https://github.com/sagarnayak/expense-tracking-public Pages you’ll see ...