JSON vs XLSX
A detailed comparison of JSON Data and Excel Spreadsheet — file size, quality, compatibility, and which format to choose for your workflow.
Technical Specifications
| Specification | .JSON | .XLSX |
|---|---|---|
| MIME type | application/json | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| Extension | .json | — |
| Standard | ECMA-404, RFC 8259 | — |
| Encoding | UTF-8, UTF-16, or UTF-32 | — |
| Allowed types | object, array, string, number, boolean, null | — |
| Container | — | ZIP (Office Open XML) |
| Max rows | — | 1,048,576 |
| Max columns | — | 16,384 |
| Released in | — | Microsoft Office 2007 |
| Variants | — | .xlsx, .xlsm (macros), .xlsb (binary) |
Strengths Comparison
.JSON Strengths
- Dead-simple — you can memorize the entire grammar on one page.
- Native parsers in every programming language.
- Human-readable and easy to debug.
- Compact — much smaller than equivalent XML.
- Frozen spec — a JSON parser written in 2010 still handles new JSON files from 2026.
.XLSX Strengths
- Much smaller than legacy .xls files thanks to ZIP + XML.
- Human-readable structure — easy to extract data programmatically.
- Supports macros (as .xlsm variant), charts, pivot tables, conditional formatting.
- Universal support: Excel, LibreOffice, Google Sheets, Numbers, pandas.
- ISO/IEC 29500 standardized.
Limitations
.JSON — Limitations
- No comments allowed — config files feel verbose.
- No trailing commas — a constant source of parse errors.
- No native date, decimal, or binary types — everything is strings or numbers.
- Easily bloated by repeated keys; large payloads compress poorly vs binary alternatives.
- Streaming is awkward — JSON wants to be parsed whole.
.XLSX — Limitations
- Macros in .xlsm are a common malware vector — disabled by default in Office.
- 1M-row limit is a cultural problem — people put too much data in Excel.
- Subtle formula differences between Excel, LibreOffice, and Sheets.
- Large files with many formulas recalculate slowly.
Frequently Asked Questions
JSON (JavaScript Object Notation) is a lightweight text format for data exchange, popularized by Douglas Crockford around 2001. JSON represents nested objects, arrays, strings, numbers, booleans, and null values in a syntax derived from JavaScript. It is the default data format for modern web APIs.
JSON files are plain text — open them in any text editor (Notepad, VS Code, Sublime Text, TextEdit). For formatted reading, use JSON-aware editors (VS Code auto-indents) or online viewers like jsonformatter.org. Every web browser displays JSON directly if you open the file locally.
Use KaijuConverter's JSON-to-CSV converter for nested data flattened into a tabular format. For simple flat JSON (array of objects), command-line tools like jq + csvkit give more control. Python's pandas and JavaScript's PapaParse also handle the conversion in one line of code.
JSON for machine-to-machine data exchange (APIs, config) — strict spec, fast parsers in every language. YAML for human-edited config files — supports comments, multi-line strings, and references. Kubernetes, Docker Compose, and GitHub Actions use YAML; REST APIs overwhelmingly use JSON.
JSON's strict specification disallows comments to keep parsers simple and unambiguous. Workarounds include JSONC (JSON with Comments, used by VS Code config), JSON5 (relaxed syntax with comments), or a convention of adding a "comment" or "_doc" field in your data.
JSON itself cannot execute code like JavaScript eval() can, making it safer than older exchange formats. However, deeply nested JSON can exhaust memory (a "billion laughs" variant) — use streaming parsers and limit recursion depth when processing untrusted input.
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