Open-source alternatives to Coordtransform

This project is a set of exercise solutions and implementation guides for visual simultaneous localization and mapping. It provides a collection of worked code examples and mathematical solutions designed to translate theoretical localization and mapping concepts into practical implementations. The repository serves as a technical companion for academic study, featuring worked answers to SLAM exercises and a system for tracking typographical and technical corrections to maintain the accuracy of the associated written work. The codebase covers spatial mathematics and robotics geometry, includ

ARKit-CoreLocation is a framework and library for synchronizing augmented reality world tracking with GPS coordinates. It enables the placement of virtual objects at precise real-world locations by anchoring digital content to latitude and longitude coordinates. The project provides tools for aligning augmented reality scene headings with geographic north and rendering directional navigation paths on real-world surfaces. It includes capabilities for drawing geographic routing lines and creating world-scale annotations that scale based on their distance from the user. The system manages geosp

language-ext is a functional programming framework for C# that provides a suite of immutable data structures and monadic types. It enables the implementation of pure functional programming patterns, utilizing containers to manage side effects, optional values, and error handling. The library is distinguished by its advanced concurrency and state management tools, including a software transactional memory system and lock-free atomic references. It also provides specialized utilities for distributed systems, such as vector clocks for causality tracking and deterministic data conflict resolution

Temporal is a distributed workflow orchestration engine designed to manage fault-tolerant, stateful, and long-running background processes. It functions as a platform for coordinating complex cross-service operations, ensuring consistency and reliability in distributed environments by decoupling workflow orchestration from task execution. The platform distinguishes itself through a deterministic, event-sourced execution model that reconstructs workflow state by re-executing code from an immutable event log. This approach isolates non-deterministic side effects into managed activities, allowin

Falcon is a minimalist Python web API framework and high-performance microservices framework. It serves as a resource-oriented API toolkit designed for building RESTful APIs and data plane services that prioritize low overhead, reliability, and scale. The framework implements an ASGI web server interface to handle both synchronous and asynchronous HTTP requests and WebSockets. It features a dedicated HTTP middleware system for intercepting network traffic and executing shared processing logic across multiple API endpoints. Its capability surface covers resource-based routing, HTTP specificat

Expr is a statically typed expression engine and domain-specific language for parsing and evaluating dynamic logic strings within Go applications. It functions as a bytecode expression evaluator that executes compiled logic with guaranteed termination and memory safety. The engine utilizes a specialized compiler and virtual machine to achieve high-performance execution. It employs static type validation during the compilation phase to ensure operand compatibility and prevent runtime crashes. The project provides a data transformation engine capable of mapping, filtering, and aggregating coll

Just is a collection of JavaScript utility libraries designed for data manipulation, functional programming, performance optimization, statistical analysis, and string processing. It provides a set of tools for deep cloning, filtering, and transforming complex objects and arrays. The project is structured as a series of zero-dependency modules, allowing utilities to be used independently to minimize bundle size. It implements functional programming patterns including currying, piping, and partial application, and provides execution control through memoization, debouncing, and throttling. The

No-as-a-Service is a lightweight, self-hosted API that returns a random humorous rejection reason as a JSON object through a single GET endpoint. It serves pre-defined rejection reasons from a static JSON array without any database, external storage, or third-party dependencies, using only Node.js built-in modules for its zero-dependency HTTP server. The API processes each request independently with no session state, caching, or persistent connections, making it a stateless REST endpoint. Its rejection reasons are stored in a simple, human-readable JSON configuration file that can be edited w

This project is a self-hosted email verification system and API designed to validate email existence and clean mailing lists on private infrastructure. It functions as a deliverability tool that confirms if email addresses are reachable by communicating with mail servers via the SMTP protocol without sending actual messages. The system is distinguished by its high-volume SMTP infrastructure, which utilizes a stateless worker architecture and message queue task distribution to scale validation tasks. It includes an SMTP proxy gateway that routes requests through SOCKS5 proxies to mask server i

This project is a multi-purpose REST API utility collection and developer suite. It serves as a centralized service for real-time information aggregation, data transformation, and a wide array of programmatic tools. The service distinguishes itself by providing a broad range of specialized content delivery endpoints, from curated daily summaries and global trending rankings to randomized entertainment content like jokes and quotes. It also functions as a real-time aggregator for environmental and network data, including weather forecasts, currency exchange rates, and public IP lookups. The c

iron-session is a stateless session management library for JavaScript that stores encrypted and signed session data directly in browser cookies. It functions as authentication middleware to verify user identity without requiring a server-side database or network lookups for session retrieval. The project provides a symmetric key encryption tool that supports versioned password rotation. This allows encryption keys to be updated across a system without invalidating active user sessions. Beyond session management, the library includes utilities to seal arbitrary data objects into secure signed

1loc is a JavaScript utility library and multifaceted toolkit providing a collection of single-line functions for common mathematical, string, date, and geometric operations. It functions as a set of functional programming helpers and data validation predicates designed to perform atomic transformations and validations. The project includes a geometry math library for calculating distances, angles, and spatial overlaps between points and rectangles, alongside a text manipulation library for casting, capitalizing, and analyzing string content. The toolkit covers broader capability areas inclu

GoTrue is a JWT identity provider and user management API. It functions as an OAuth 2.0 compliant server that handles user registration and authentication while issuing signed JSON Web Tokens to control access to protected API resources. The service integrates external identity providers to allow users to sign in using third-party accounts. It also includes an SMTP notification service for delivering password resets, signup confirmations, and account recovery emails. The system covers broader capabilities for user account management, including the ability to update user profiles and manage c

Play is a full-stack reactive web framework for Java and Scala. It provides a comprehensive development platform for building scalable web applications and RESTful APIs using a stateless and non-blocking architecture designed for high concurrency. The framework emphasizes high-velocity development through dynamic code reloading, which allows developers to update applications and verify changes without performing a full restart. Its capability surface covers the construction of JSON-based web endpoints, server-side logic for the JVM, and the implementation of scalable web architectures.

Backendlore is a collection of architectural guides and patterns for building stateless JSON HTTP APIs using Node.js. It focuses on designing backend systems that offload session and application state to external databases and in-memory stores to facilitate horizontal scaling. The project provides specific implementation standards for REST APIs, including request payload validation and the use of cryptographically signed cookies for session management. It details a strategy for file management that combines local filesystem caching for high-speed delivery with cloud object stores for long-ter

AlgoXY is a functional programming educational book and technical publication produced as a LaTeX digital book. It serves as a programming education resource and library focused on functional algorithms and data structures. The project provides a collection of persistent data structures, such as trees and heaps, designed for immutable state management. It includes a series of implementation exercises and verified answers to teach core computer science concepts through the practical application of functional logic. The content covers the design of persistent data structures and the implementa

date-fns is a JavaScript date utility library providing a collection of pure functions for manipulating, formatting, and calculating dates and times. It serves as an immutable date manipulation library and a tool for time zone management, ensuring that date transformations are performed without modifying the original date objects. The library functions as a date formatting tool that converts date objects into human-readable strings using custom patterns and international locales. It includes a specific toolset for adjusting and calculating date representations across different geographical re

This project provides a set of software architecture guidelines, Lisp coding standards, and functional programming patterns for Clojure development. It establishes best practices for implementing declarative logic and managing shared state through the use of persistent data structures and atomic references. The guide covers standards for documenting public APIs and organizing project directories to ensure portable library distribution. It details the application of consistent formatting and naming rules to improve source code readability and team collaboration. The scope extends to idiomatic

Cesium is a JavaScript library designed for rendering high-precision 3D globes and 2D maps within web browsers. It functions as a visualization engine that leverages hardware-accelerated graphics to display complex geographic data, terrain, and imagery. The library distinguishes itself through a modular architecture that supports the streaming of massive geographic datasets. By employing tiled data delivery and hierarchical level-of-detail optimization, it maintains performance while navigating large-scale environments. It also includes a time-dynamic state management system, which synchroniz

Blocky is a stateless DNS proxy that functions as a network-wide ad-blocker and content filter. It operates as a single binary or Docker container with no database or persistent state, accepting DNS queries over UDP, TCP, HTTPS, TLS, QUIC, and HTTP/3 through a unified plugin-based query pipeline. The core of the system is a client-group policy engine that assigns devices to named groups and applies per-group blocklists, allowlists, and upstream resolvers, with all configuration changes applied through hot-reloading without requiring a restart. The project distinguishes itself through its modu

Pollinations is a generative AI content platform and model gateway that provides a unified multimodal API for producing text, images, audio, and video. It functions as an AI monetization framework, managing user wallets, spending limits, and revenue sharing for applications that integrate generative tasks. The platform includes a specialized web generator that transforms natural language prompts into functional single-page websites. It distinguishes itself by offering a stateless public API that allows for the generation of media and text via HTTP requests without requiring user authenticatio

This project is a comprehensive collection of frontend development best practices and standards. It provides guides for writing semantic HTML, efficient CSS, and functional JavaScript to improve overall web performance and accessibility. The repository establishes frameworks for modern CSS architecture, focusing on specificity management and the use of Flexbox and Grid for predictable layouts. It outlines patterns for functional JavaScript programming, emphasizing the use of pure functions and composition to reduce execution time and dependency bloat. The guidelines cover several core capabi

Rainloop Webmail is a self-hosted, browser-based email application that connects to external mail servers using IMAP and SMTP protocols. It operates as a stateless client, fetching data directly from servers without requiring a local database to store messages. The system supports multi-account email management, allowing users to link multiple email identities to a single session for simultaneous access across different browser tabs. It includes a plugin-based extension system and tools for user interface customization and branding. The application provides capabilities for email workflow au

PostgREST is a standalone server process that automatically transforms a relational database schema into a fully functional RESTful API. By querying system catalogs at startup, it maps tables, views, and stored procedures into standardized web endpoints, allowing developers to build backend services by focusing exclusively on database design. The service functions as a declarative engine that translates HTTP requests and query parameters directly into native SQL operations. It maintains stateless request processing and integrates connection pooling to manage high-frequency interactions effici

BrasilAPI is a REST API gateway that aggregates and exposes official Brazilian public data from fragmented government sources. It functions as a multi-provider data aggregator that normalizes heterogeneous information into a standardized JSON schema for consistent delivery. The system utilizes a multi-provider fallback pipeline to ensure reliable data resolution, querying several external APIs in sequence if a primary provider fails. It also incorporates a caching proxy gateway to reduce latency and avoid redundant requests for frequently accessed public data. The platform covers a broad ran

s2client-proto provides a set of structured data definitions and language-neutral communication protocols used to exchange information between an external client and the StarCraft II engine. It utilizes protocol buffer definitions to establish a binary serialization schema for these data exchanges. The project defines the underlying communication layer necessary for game engine automation, game state analysis, and the development of software agents for competitive gaming. The framework covers interface definition languages to ensure compatibility across programming languages and employs sche

Imaginary is a self-hosted HTTP server for image processing that applies transformations like resizing, cropping, rotating, and format conversion through URL parameters. It operates as a stateless request-response pipeline, processing images fetched from remote URLs or served from a local directory without requiring client-side dependencies. The server distinguishes itself through its security and access control capabilities, offering optional API key validation, HMAC-signed URL verification, and remote origin whitelisting to restrict which image sources are permitted. It also provides a heal