HelloCSV - A free FlatFile alternative

Product Introduction

1. HelloCSV is a frontend-only JavaScript library designed to simplify CSV/TSV file imports in web applications without requiring backend processing or React dependencies. It provides a customizable four-step workflow (column mapping, data transformation, validation, and preview) through a 99KB gzipped package that can be implemented via CDN or npm.
2. The core value lies in offering enterprise-grade data import capabilities with zero data transmission to external servers, addressing both developer productivity and data security concerns through its client-side execution model.

Main Features

1. The library processes CSV files entirely in the browser using JavaScript Web Workers, ensuring sensitive data never leaves the user's device while maintaining performance through parallel processing.
2. Developers can integrate the importer via script tags or module imports, with full TypeScript support and compatibility across vanilla JavaScript, React, Vue, Angular, and other frameworks through adapter patterns.
3. Advanced multi-sheet parsing enables relational data handling, automatically splitting combined datasets into normalized tables (e.g., separating employee and company records) using configurable primary/foreign key relationships.

Problems Solved

1. Eliminates the need for custom CSV parsing scripts by providing pre-built handlers for edge cases like irregular delimiters, mixed encoding formats, and spreadsheet-style date conversions.
2. Serves full-stack developers working on data-intensive applications requiring secure client-side processing, particularly in healthcare, finance, and SaaS platforms with strict compliance requirements.
3. Enables rapid implementation of GDPR/CCPA-compliant data upload features for user-facing applications like CRM systems, inventory management tools, and analytics dashboards requiring bulk data imports.

Unique Advantages

1. Unlike Flatfile's API-driven approach, HelloCSV operates as a MIT-licensed open-source solution with permanent free usage, allowing full code audits and white-label customization without subscription costs.
2. The library implements real-time data transformation pipelines using WebAssembly-powered converters for operations like phone number formatting, currency normalization, and regex-based pattern enforcement during uploads.
3. Combines the lightweight footprint of 99KB with built-in features like drag-and-drop upload, 10MB-20MB file size limits, and automatic column type detection that outperforms similar tools requiring 3-4x larger dependencies.

Frequently Asked Questions (FAQ)

1. How does HelloCSV ensure data privacy? All processing occurs client-side through isolated Web Workers, with optional Web Crypto API integration for encryption before any potential network transmission to your backend.
2. Can I use this with React or Next.js projects? Yes, while optimized for framework-agnostic use, HelloCSV provides React hooks and SSR-compatible builds that integrate seamlessly with Next.js static generation and hydration workflows.
3. What file encodings and formats are supported? The library automatically detects and processes UTF-8/16/32, ISO-8859-1, and Windows-1252 encodings across CSV/TSV files, with experimental XLSX parsing via SheetJS integration in advanced configurations.
4. How customizable is the UI component? Developers can override CSS custom properties for theming, extend the core validation engine with custom rules, and replace default UI elements using documented slot patterns without modifying source code.
5. Does it support legacy browsers? The build targets ES2017 compatibility, functioning in all modern browsers while providing optional Babel transforms for Internet Explorer 11 support through separate legacy bundles.