Open-source alternatives to Log4js Node

This project is a structured logging framework and library for Node.js applications. It produces machine-readable log records in JSON format with tiered severity levels, ensuring consistent parsing and centralized storage. The system includes a log stream manager for routing records to multiple destinations, such as files and consoles, and a command line interface for filtering, formatting, and visualizing raw JSON log streams. It supports the creation of child loggers that inherit parent configurations and merge additional contextual metadata. The framework covers a broad range of operation

SwiftyBeaver is an extensible logging framework for Swift that routes log output to multiple destinations simultaneously, including the Xcode console, local files, and remote cloud services. It supports recording messages at distinct severity levels with corresponding visual styling, and can attach arbitrary contextual data such as numbers, arrays, or dictionaries to log entries without requiring manual string conversion. The framework distinguishes itself through destination-based log routing, where each output target can have its own independent format and filter configuration managed by a

Logrus is a structured logging library for Go that produces machine-readable output using key-value pairs and JSON formatting. It serves as a pluggable logging framework providing a thread-safe event logger with configurable mutex locking to manage concurrent writes across multiple goroutines. The project distinguishes itself through a pluggable hook system that routes log entries to external services or custom destinations. It also features a contextual logger capable of attaching persistent metadata and request-scoped fields to entries to improve traceability. The framework covers broad ob

EasyLogger is a lightweight C/C++ logging library and asynchronous framework designed for embedded systems, IoT devices, and wearables. It functions as a resource-efficient logger and flash memory manager, providing tools for low-level debugging and system event recording with minimal ROM and RAM requirements. The project distinguishes itself through an asynchronous logging model that buffers messages to a separate thread, preventing logging operations from blocking real-time application execution. It includes a specialized flash memory manager that utilizes circular buffering to persist logs

Lumberjack is a log rolling library for Go that manages the lifecycle of log files through size-based rotation and backup cleanup. It functions as a log retention manager to prevent disk exhaustion in Go services. The project optimizes log storage by compressing rotated files using the gzip algorithm and generating unique filenames via timestamped backups. It implements a retention policy that prunes historical records based on a maximum number of backups or a specified file age. The library implements the standard Go writer interface to integrate with logging libraries, providing a mechanis

XCGLogger is a Swift logging framework designed to record application events with automatic metadata, such as timestamps and line numbers, to assist in troubleshooting and debugging. The project features an asynchronous log router that offloads writing operations to background queues and utilizes deferred evaluation to avoid expensive string construction when a log level is inactive. It includes a file-based log manager that handles persistent storage with automatic rotation based on file size or age, as well as a custom formatter for applying date formats and ANSI color codes to console outp

NLog is an open-source logging framework for .NET that functions as a structured logging library and log routing engine. It captures log events with named parameters as searchable data rather than plain text and directs these messages to various output destinations based on severity and source. The framework is designed as an extensible platform, supporting custom targets, layout renderers, and filters that can be loaded from external assemblies or defined in code. It features a dynamic configuration system that allows logging targets, rules, and layouts to be updated via XML or programmatic

This project is a learning guide and collection of study notes designed to teach Node.js backend development. It provides a comprehensive core API reference and practical demonstrations for implementing server-side logic, network programming, and system APIs. The guide specifically covers advanced technical domains including process management for scaling applications via clusters and child processes, as well as network programming for building TCP, UDP, and HTTP services. It also includes detailed instructional material on security implementation, focusing on cryptographic hashing and encryp

Coost is a concurrent network framework and coroutine scheduler designed for building high-performance TCP, HTTP, and RPC services. It provides a set of tools for handling non-blocking IPv4 and IPv6 communication, integrating SSL encryption and a lightweight execution engine that manages concurrent tasks using shared stacks. The project features a specialized JSON RPC implementation for exchanging structured data over encrypted connections and a high-performance logging system. This logging infrastructure supports topic-based routing, frequency filtering, and automated stack trace capture for

Consola is a diagnostic logging utility and log output manager that provides a unified interface for Node.js and web browser environments. It functions as a scoped logging framework and a tool for capturing user text, confirmations, and selections through interactive console prompts. The project distinguishes itself through a system for creating specialized logger instances with inherited defaults and unique tags for contextual tracking. It also features a pluggable reporter interface that allows for the redirection of standard output to custom logging destinations and external reporters. Th

log.io is a real-time log monitoring system designed for streaming and visualizing system logs in a web browser as they are generated. It consists of a TCP log aggregator that collects formatted messages from remote sources and a file-based log streamer that monitors local files for changes. The system provides a web-based log viewer capable of ad-hoc visualization, allowing users to route specific active log streams to different screens for targeted monitoring. This is supported by a centralized message broker that redistributes incoming logs to web clients. The platform covers centralized

spdlog is a high-performance C++ logging library designed to record diagnostic messages and application events. It serves as an asynchronous logging framework and thread-safe library that coordinates access across concurrent threads to maintain message integrity. The project functions as a multi-target log router, distributing single events to multiple destinations such as consoles, files, and system daemons. It includes a log rotation manager that handles file lifecycles through basic, rotating, or daily rollover strategies to prevent disk exhaustion. The library covers a broad range of cap

Loguru is a Python logging library and thread-safe framework designed for recording system events and diagnostic messages. It functions as a structured logging tool that can serialize messages into JSON strings with metadata for automated parsing and analysis. The library includes a specialized exception tracker that captures unhandled crashes across main and background threads, rendering detailed stack traces that include local variable values. It further distinguishes itself through a unified routing pipeline that can intercept messages from the standard library logging module and dispatch

Logspout is a container log aggregator, forwarder, and routing engine designed to gather logs from Docker containers and route them to centralized external logging systems. It functions as a network-based utility that pipes container output to remote destinations such as syslog or TCP endpoints. The system features a dynamic routing engine that allows the creation and updating of log routing configurations and destination filters in real time via an HTTP interface without restarting the service. It utilizes an adapter-based architecture, enabling the development of custom output modules and t

Monolog is a logging library that implements the PSR-3 standard to ensure interoperable log handling across PHP applications. It provides a standardized interface for managing log records, allowing the logging system to remain replaceable across different libraries and frameworks. The library features a routing engine that distributes log messages to multiple destinations, including files, sockets, databases, and external web services. It enables severity-based routing and integration with third-party cloud platforms, messaging apps, and email services for centralized log management. To supp

Fluentd is a unified logging layer and distributed event router that collects, parses, and routes log data from diverse sources to various storage backends. It functions as a log forwarding agent and pipeline orchestrator, transforming raw unstructured log strings into formatted objects using structured log parsing. The project utilizes a plugin-based pipeline architecture to route data through independent input, filter, and output stages. It differentiates itself through tag-based event routing, which uses regular expression patterns to direct specific data streams to their intended destinat

HAProxy is a high-performance TCP and HTTP proxy that distributes traffic across multiple backend servers to ensure availability and fault tolerance for critical services. It operates in either TCP or HTTP mode, with an event-driven, single-threaded reactor that handles tens of thousands of connections without context switching, and supports kernel-level data transfer to minimize memory usage and latency. What distinguishes HAProxy is its configuration-file-first design, where all load-balancing rules and runtime behavior are defined in a declarative text file parsed at startup. It embeds a L

structlog is a structured logging library for Python that treats log entries as dictionaries instead of strings. This data-centric approach enables machine-readable output and precise data analysis by generating log entries as key-value pairs. It functions as both a standalone logging framework and a compatibility layer that adds structured capabilities to the Python standard library logging module. The library features a processor-pipeline architecture that passes log dictionaries through a sequence of functions to modify events or add metadata before final rendering. It includes a contextua

This project is a JavaScript logging utility and namespace-based debugger used for printing formatted, color-coded debug messages to the console in Node.js, web browsers, and Deno. It serves as a console output formatter and execution time profiler to help identify bugs and track program flow. The system manages debug visibility through named namespaces, allowing specific groups of messages to be enabled or disabled via environment variables. It distinguishes different modules in the output stream by assigning specific colors to these namespaces. The utility includes capabilities for measuri

glog is a C++ logging framework designed for recording application events and system diagnostics. It provides a stream-based interface for capturing debugging information and managing system event persistence. The library includes a stack trace logger that captures execution call stacks and resolves memory addresses into readable function names. It also features a dedicated error handling module to manage system shutdown and reporting during fatal failures. Log lifecycle management is handled through automatic rotation and deletion of old files to prevent disk space exhaustion. The framework

Uptrace is an OpenTelemetry-based observability platform designed to collect, store, and analyze distributed traces, metrics, and logs. It functions as a centralized logging backend, a distributed tracing system, and a metrics engine to monitor application performance and system health. The platform is distinguished by AI-powered operational capabilities, allowing users to query telemetry data and manage monitoring dashboards using natural language. It specifically includes specialized monitoring for generative AI pipelines, tracking token usage and response quality for LLM interactions and r

This is a structured logging library designed to produce logs using key-value pairs, severity levels, and machine-readable formats. It provides a toolkit for creating logs that are consistent for both human review and machine parsing. The project is distinguished by its focus on terminal visualization, using a styling system to apply colors and prefixes to log entries for improved readability in consoles. It also includes a specialized adapter to convert standard library log calls into structured events by inferring severity levels from message prefixes. The library manages metadata through

Morgan is a Node.js HTTP logging middleware designed to record incoming requests and outgoing responses. It captures request metadata and timing to facilitate API request auditing and server performance monitoring. The project utilizes token-based string interpolation and custom log tokens to extract specific properties from HTTP objects. It supports multi-destination logging by routing formatted log strings to various writable streams and employs log output sanitization to escape control characters. Additional capabilities include predicate-based log filtering to conditionally omit entries

cf2dns is a tool for automating IP performance screening and DNS record updates. It functions as a DNS optimizer and IP filter that identifies high-performance Cloudflare IP addresses and updates DNS records via API to improve website loading speeds. The project provides a dynamic DNS route manager that maps optimized IP addresses to specific network carriers. This process includes regional connection defense to mitigate network interference and bypass connection blocks using curated IP pools. The system handles both IPv4 and IPv6 record management and includes scheduling mechanisms for regu

Ergo is a distributed actor framework for Go that implements the Erlang distribution protocol, enabling the construction of resilient, concurrent applications that can communicate transparently with Erlang/OTP nodes. At its core, it provides an actor model with isolated lightweight processes, priority-ordered mailboxes, and a meta-process architecture that separates blocking I/O from sequential message handling to prevent actor freezing. The framework includes a Raft-inspired cluster consensus system for leader election and automatic failover, along with OTP-style supervision trees that organi

re-frame is a functional framework for building single-page applications in ClojureScript. It provides a centralized, immutable database that serves as the single source of truth for the entire application state, enforcing a strict unidirectional data flow where events trigger state transitions and subsequent view updates. The framework distinguishes itself through a reactive signal graph and an interceptor-based middleware pipeline. By treating application logic as a sequence of data-driven events and declarative side effects, it decouples business logic from the view layer. This architectur

Signale is a highly configurable logging library for Node.js applications that provides 16 built-in loggers, each with distinct badges, colors, and labels for different message types. It functions as a console logger that displays timestamps, labels, badges, and filenames in configurable log output, and includes an interactive mode that overwrites previous messages in place for real-time progress indicators. The library distinguishes itself through several advanced capabilities, including a custom logger factory that lets developers create new logger types with unique badges, colors, and labe