Comma-Separated Values (.csv)
RFC StandardníComma-Separated Values (CSV) is a ubiquitous plain-text format for tabular data, where each line represents a data record and fields are separated by delimiter characters.
Převést XLSX do CSV
Bezplatný konvertor z XLSX do CSV v prohlížeči. Převeďte soubory okamžitě ve svém zařízení.
Komprese CSV online
100% soukromá komprese v prohlížeči – soubory nikdy neopustí vaše zařízení
Zkontrolovat a metadata
Operační systémy a analyzátory souborů identifikují soubory CSV kontrolou počáteční binární sekvence bajtů:
Podpis hlavičky na úrovni bajtů (Magic Bytes)
Operační systémy a analyzátory souborů identifikují soubory CSV kontrolou počáteční binární sekvence bajtů:
HEXADECIMÁLNÍ PODPIS (OFFSET 0):
Plain TextASCII REPREZENTACE: ASCII / UTF-8
Standardizace: RFC 4180 / IETF
Technické specifikace
| Architektura kontejneru | Delimited flat text file representing tabular data rows and columns |
| Komprese | Gzip / Deflate achieves 85%-95% compression on repetitive tabular records |
| Endiantita bajtů | UTF-8 text stream (optional UTF-8 BOM EF BB BF used by Excel) |
| Barevné prostory | Not applicable |
| Kanály a struktura | Row records delimited by CRLF with columns delimited by commas |
| Max. rozměry | Unbounded; streamable to gigabytes without loading entire file in memory |
| Průhlednost | Not applicable |
| Streamování a progresivní načítání | Native line-by-line stream processing supported by all data pipelines |
Technická srovnávací matice: CSV vs konkurence
| Technický atribut | CSV (Aktuální) | Excel (XLSX) | Parquet | JSON |
|---|---|---|---|---|
| File Type | Plain text flat table | Zipped XML spreadsheet | Binary columnar storage | Hierarchical text |
| Multiple Sheets | No (single flat table only) | Yes (multiple workbooks and sheets) | Partition-based storage | Nested arrays and objects |
| Data Types | Untyped raw text | Typed cells, formulas, formatting | Strict binary column types | Primitive types (string, number, bool) |
| Big Data Analytics | Slow (requires reading every row linearly) | Not suitable for big data | Ultra-fast (column pruning & predicate pushdown) | Moderate |
Běžné režimy poškození a příručka pro obnovení v hex
⚠️ Columns shift to the right or row counts do not match.
Hlavní příčina: A text field containing an unescaped comma without surrounding quotation marks.
Obnovení: RFC 4180 requires fields containing commas to be wrapped in double quotes: "Smith, John".
⚠️ Accented characters render as strange symbols (mojibake like é instead of é) in Excel.
Hlavní příčina: Excel opened a UTF-8 CSV assuming the legacy Windows ANSI/CP1252 character encoding.
Obnovení: Prepend the 3-byte UTF-8 Byte Order Mark (0xEF 0xBB 0xBF) to the beginning of the file.
Bezpečnostní analýza a vektory útoků na parser
CSV files open directly in spreadsheet software like Excel and Google Sheets, exposing users to Formula Injection (CSV Injection) attacks.
Známé vektory útoků
- Formula Injection: Cells starting with '=', '+', '-', or '@' executing spreadsheet macros or DDE commands (e.g. '=cmd|' /C calc'!A0').
- Data exfiltration via HYPERLINK() formulas sending sensitive cell data to remote attacker servers upon click.
Doporučené bezpečnostní postupy: When exporting user data to CSV, prepend a single quote (') or tab to any cell starting with '=', '+', '-', or '@' to force plain text rendering in Excel.
Historický vývoj a milníky
Klíčové výhody a přednosti
- Maximum simplicity: readable in any text editor and importable into every database and spreadsheet.
- Extremely fast line-by-line streaming without building a full in-memory DOM.
- Minimal overhead: no verbose tag syntax or schema definitions.
Technická omezení a nevýhody
- No standard data types: numbers, dates, booleans, and text are all stored as raw strings.
- No support for multiple sheets, cell formatting, formulas, or metadata.
- Delimiter conflicts (commas inside text, decimal commas in European locales) cause frequent parsing bugs.
Zajímavé technické drobnosti
- In many European countries where commas are used as decimal points, semicolons (;) are used instead of commas as CSV separators.
- Microsoft Excel historically required a UTF-8 BOM (0xEF 0xBB 0xBF) to correctly display non-ASCII accented characters.
Často kladené technické otázky
What is RFC 4180?
RFC 4180 is the official IETF standard for CSV. It mandates that fields containing commas, line breaks, or double quotes must be enclosed in double quotes, and internal quotes must be escaped by doubling them ("").
Why do CSV files open with corrupted characters in Excel?
Older versions of Microsoft Excel default to the local Windows code page (like Windows-1252) rather than UTF-8 when opening CSV files directly. Adding a UTF-8 BOM (Byte Order Mark) at the start of the file forces Excel to decode UTF-8 correctly.
Související konverzní páry pro CSV
Export Microsoft Excel spreadsheets into clean, comma-separated plain text tables.
Import CSV tabular data into formatted Microsoft Excel XLSX workbooks.
Import tabular CSV spreadsheet records directly into indexed SQLite database tables.
Extract table records and rows from SQL INSERT statements into standardized comma-separated CSV spreadsheets.
Extract multidimensional scientific datasets and numerical matrices from HDF5 (.h5) into tabular CSV format.
Flatten multidimensional NetCDF (.nc) climate and oceanographic variables into comma-separated CSV spreadsheets.
Convert electronic business cards (vCard / VCF) into tabular CSV contact lists for Excel and Google Contacts.