Talaan

A zero-dependency spreadsheet & CSV reader for .NET.

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Talaan (Filipino for record / list / table) reads .xlsx and CSV files into a simple, typed cell grid — with no external dependencies. No Excel Interop, no ClosedXML, no OpenXML SDK. An .xlsx is just a zip of XML, and Talaan walks those parts directly using only the .NET base class library (System.IO.Compression + System.Xml).

Why

• Zero dependencies. Nothing to audit, nothing to update, no transitive surprises. One small assembly.
• Typed cells. Numbers come back as numbers, dates as DateTime, booleans as bool — not stringly-typed guesses. Excel serial dates and shared strings are resolved for you.
• Raw grid, no magic. Talaan hands you the sheet exactly as laid out. You decide which row is the header and which rows to skip — perfect for real-world files with title rows, sections, and blanks.

Install

dotnet add package Talaan

Quick start

using Talaan;

// From a file…
SheetData sheet = Spreadsheet.ReadFile("members.xlsx");

// …or a stream (an upload, say), dispatched by file name:
SheetData sheet = Spreadsheet.Read(uploadStream, fileName);

for (int r = 0; r < sheet.RowCount; r++)
{
    CellValue name = sheet.At(r, 1);   // row r, column B
    if (name.Kind == CellKind.Text)
        Console.WriteLine(name.Text);
}

Every cell is a CellValue:

public readonly record struct CellValue(
    CellKind Kind,        // Empty | Text | Number | Date | Boolean
    string?  Text,
    double?  Number,
    DateTime? Date,
    bool?    Boolean);

cell.IsBlank      // empty, or whitespace-only text
cell.AsString()   // best-effort display: invariant numbers, ISO-8601 dates

Supported formats

Format	Extension	Notes
Excel	.xlsx	First worksheet. Shared strings, inline strings, booleans, numbers, and style-based date detection.
CSV	.csv, .txt	RFC-4180: quoted fields, escaped "", embedded commas and newlines.
TSV	.tsv	Tab-delimited.

You can also bypass detection: Spreadsheet.Read(stream, SpreadsheetFormat.Xlsx).

Design notes

• Dates. .xlsx stores dates as serial numbers; Talaan inspects the workbook stylesheet (cellXfs → number format) to decide whether a numeric cell is a date, then converts via the OLE Automation epoch. Ambiguous m (month vs. minute) is ignored in favour of unambiguous y/d.
• Column alignment. Cell references (A1, AB12) are honoured, so skipped/blank cells become CellValue.Empty and columns stay aligned.
• Streaming input. Non-seekable streams are buffered automatically for zip access.

Scope (by design)

Talaan reads; it does not write. It reads the first worksheet. Formulas are returned by their last cached result. If you need multi-sheet, writing, or styling, this isn't that library — and that is the point.

License

MPL-2.0 © BaryoDev