Open-source alternatives to Javascript

Underscore is a JavaScript utility library providing a suite of functional programming and data manipulation helpers. It serves as a framework for transforming data collections, composing functions, managing objects, and performing precise data type validation without modifying core language prototypes. The project includes a functional programming toolkit designed to control function execution timing and behavior through techniques such as debouncing, throttling, and partial application. It also provides a dedicated object manipulation utility for cloning, merging, picking, and omitting prop

Dollar is a functional programming library for Swift that provides a comprehensive toolkit for collection manipulation, string processing, mathematical calculations, and date and time management. It serves as a utility suite for filtering, aggregating, and restructuring arrays and dictionaries. The project implements functional programming patterns such as currying, memoization, and function composition. It also features a chainable wrapper interface that allows multiple data transformations to be applied sequentially before extracting a final result. The library covers a wide range of capab

Ramda is a functional JavaScript standard library and toolset for immutable data transformation and composition. It provides a comprehensive suite of pure utility functions designed to enable declarative data processing pipelines. The library is distinguished by its use of automatic function currying and a data-last argument order. These design patterns allow multi-argument functions to be partially applied, simplifying the construction of processing chains where data is passed through a sequence of operations. The toolkit covers broad data manipulation capabilities, including list processin

validator.js is a JavaScript string validation and sanitization library. It provides a set of functions to verify that strings match specific patterns—such as emails, URLs, and alphanumeric formats—and a toolkit for cleaning and transforming text input to remove prohibited characters and trim whitespace. The library includes utilities for standardizing email addresses by lowercasing domains and removing sub-addressing markers. It also functions as an HTML entity escaper, replacing special characters with entities to prevent the browser from executing text as code. The project covers capabili

Validator.js is a library of pure, stateless functions designed for the validation and sanitization of string data within any JavaScript environment. It provides a modular suite of tools to verify that user-provided information conforms to specific formats, such as emails, URLs, and dates, while simultaneously cleaning untrusted input to mitigate security risks. The library distinguishes itself through a design that avoids platform-specific APIs, ensuring consistent execution across browsers, servers, and edge runtimes. By utilizing a pre-compiled regular expression engine and a pure data tra

Hypothesis is a property-based testing library for Python that automatically generates randomized input data to identify bugs and edge cases. It functions as an automated edge case finder and test data generator, creating diverse synthetic datasets based on defined strategies to stress test application logic. The library includes a failing case shrinker that simplifies complex failing test inputs into the smallest possible examples to accelerate debugging. It also provides a mechanism for bug reproduction simplification by reducing the size of the input that triggers a failure. The project c

Faker is a PHP library for creating realistic synthetic data used for testing, prototyping, and populating database entities. It serves as a test data generator and localized mocking tool capable of producing synthetic names, addresses, and identifiers specific to various countries and languages. The library provides mechanisms to ensure data consistency and quality, including deterministic seeding to produce identical data sequences across executions and stateful uniqueness tracking to prevent duplicate values. It also supports probability-weighted optionality to simulate missing data and cu

Faker is a synthetic data generation library used to create realistic but fake information, such as names, addresses, and phone numbers, for software testing and database population. It functions as a tool for producing synthetic test data to fill development databases with records that simulate production environments. The library provides localized data generation, allowing synthetic information to be customized for specific geographic regions and language formats. It also includes a mechanism for unique value enforcement to prevent the repetition of generated data by tracking and rejecting

This PHP library provides tools for generating and validating universally unique identifiers according to RFC 4122 standards. It implements a generation tool for creating version 1, 3, 4, and 5 identifiers, as well as sequential and Nil UUIDs. The library features specialized capabilities for transforming identifiers between hexadecimal strings, binary bytes, integers, and date objects. It supports the generation of sequential identifiers to improve database indexing and storage performance, as well as deterministic name-based identifiers using MD5 or SHA-1 hashing. The project includes a va

Faker is a Ruby library used to generate randomized, realistic placeholder information for testing and development. It produces synthetic data to populate databases and test application logic without the use of real user information. The library provides localized data generation, using region-specific formats and strings for names, addresses, and phone numbers. It supports deterministic output through seedable random number generation, ensuring that sequences of fake data can be repeated across different test runs. The generator covers a wide range of domains, including personal identity, f

Valibot is a modular, type-safe schema library for validating and parsing structural data in TypeScript environments.

FactoryBot is a Ruby library for generating complex test objects and their associations, serving as a dynamic alternative to static fixture files. It provides a system for defining reusable data blueprints with default attributes and inheritance to produce consistent test records. The tool distinguishes itself through flexible instantiation strategies, allowing users to control whether objects are persisted to a database, built in memory, or created as stubs. It manages data uniqueness via a sequence generator for incremental values and uses traits to bundle shared attributes into reusable mo

This project is a jQuery-based form validation library designed to verify HTML form input values on the client side before submission. It functions as an input validator that enforces data integrity constraints through rule-based verification and value normalization. The library focuses on web accessibility compliance by linking error messages to input fields via ARIA attributes, ensuring that screen readers can announce validation failures to the user. The system supports the creation of custom validation rules and the transformation of raw input strings through a normalization pipeline. Co

Alice is a PHP test data generator and fixture library used to automate the creation of large sets of fake objects and entities. It functions as an object hydrator and random data provider, allowing users to define the structure and attributes of dummy test data in markup or arrays to simulate specific application states. The library distinguishes itself through a template-based system that supports fixture inheritance to reduce data duplication. It utilizes a flexible instantiation model that allows for custom factory integration, method invocation, and property hydration via reflection or c

Factory Boy is a dynamic test fixture framework and data generation tool for Python. It serves as a replacement for static fixtures by providing a system to create complex Python objects and database models through programmable blueprints. The project differentiates itself by offering specialized integration with Object Relational Mappers to manage persistence within database sessions. It enables the creation of complex object hierarchies using sub-factories and recursive composition to resolve dependent related objects. The framework provides capabilities for synthesizing realistic random d

Hypothesis is a Python property-based testing library and data generation engine. It enables the discovery of edge cases and bugs by generating a wide range of randomized inputs based on defined strategies and shrinking complex failing examples to their smallest possible form. It also functions as a state machine testing framework to verify system behavior across sequences of interdependent operations. The project features a fuzzing integration layer that converts raw byte buffers from coverage-guided fuzzers into structured test cases. It includes a persistence mechanism to store and synchro

Chance is a JavaScript library for generating random data, designed to produce realistic test data for automated tests and prototypes. It uses a Mersenne Twister pseudo-random number generator that accepts an optional seed value, enabling reproducible sequences of random values across multiple runs. The library provides a wide range of generators for common data types, including random integers, floats, booleans, characters, strings, and dates, all with configurable ranges and character pools. It can generate realistic geographic data like addresses, as well as financial data such as credit c

AntiZhaPian is a social engineering framework and fraud simulation application. It generates fake security center dashboards and anti-fraud interfaces designed to deceive users into believing that official security software is installed. The project functions as a simulation tool that mimics the visual appearance and behavior of anti-fraud applications. It uses template-based rendering and state-driven UI simulation to create synthetic dashboards with dynamic dates and fake status indicators. The application includes a user profile management interface for viewing and updating personal accou

Go Package of validators and sanitizers for strings, numerics, slices and structs

Fuzzywuzzy is a Python library and text processing utility designed to calculate similarity scores between strings. It functions as a text similarity scoring engine and an approximate string matching tool used to identify the closest textual matches within a list of candidate strings. The library provides a suite of tools for measuring the degree of similarity between pieces of text, accounting for typos and formatting differences. These capabilities include extracting the best match from a candidate list and performing fuzzy string matching through various scoring methods. The toolset cover

ozzo-validation is a programmable data validation library for Go that verifies structs, maps, and primitive types using a declarative, rule-based approach. It functions as an interface-based validator, allowing for the recursive checking of nested data structures and custom types without the use of struct tags. The framework distinguishes itself as a context-aware validation engine, supporting the propagation of request-scoped data to rules that depend on external state. It provides extensive extensibility through custom rule definitions and the ability to override default failure text with l

Beancount is a plain-text double-entry accounting system. It enforces zero-sum transactions, organizes accounts into a hierarchical five-type tree, and verifies balances at specific dates using precision-derived tolerances. Transactions are recorded in plain-text files with a strict syntax that supports currency-specific rounding, automatic interpolation of missing amounts, and comprehensive metadata including tags, links, and payee annotations. Beyond core bookkeeping, Beancount offers investment portfolio tracking with lot-based cost basis management, configurable booking strategies (FIFO,

Arktype is a TypeScript runtime validation library and schema orchestrator. It synchronizes TypeScript types with runtime data validation, allowing users to define type-safe schemas that ensure unknown data adheres to specific structures during application execution. The project distinguishes itself by using set-theory type analysis to determine intersections and subtype compatibility, alongside JIT-compiled validation functions for optimized performance. It supports advanced type modeling through branded type constraints, recursive alias resolution, and the ability to generate runtime valida

Closure Library is a JavaScript standard library and utility toolset designed for building large-scale web applications. It provides a collection of core utility modules and standardized APIs to simplify complex application logic and state management. The project is built as a modular framework using a namespace-based module system to prevent global scope pollution. It is specifically designed for use with the Closure Compiler to enable aggressive dead-code elimination and minification, reducing the final delivery size in production. To ensure reliability in large projects, the library utiliz

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

sd is a command line text manipulation utility designed for searching and replacing text patterns across multiple files. It functions as a regex-based find and replace tool that allows for in-place file editing directly from the terminal. The project supports both regular expression replacements, including the use of capture groups for complex transformations, and fixed string replacement for literal text substitutions. It specifically handles multi-line text replacement by processing file contents as single blocks to match patterns that span across newline characters. The tool provides capa