The JSON-Slayer

JSON flattening means converting deeply nested JSON objects into single-level key-value pairs. When you have complex API responses or multi-level data, databases, spreadsheets, and analytics tools cannot process them directly. After flattening, keys like user.profile.name are created, which any system can understand.

JSON-Slayer uses PHP server-side processing, so your browser’s CPU is not used at all. This tool easily handles 5MB+ JSON files. For large payloads the output automatically enters preview mode — the first 1,000 lines are shown; the rest can be obtained via Download or Copy.

• Client-side zero processing
• No restriction up to server memory limit
• Preview limit: 1,000 lines (full data downloadable)

Absolutely not. Your JSON data comes to the server only for processing and the result is returned immediately — it is not saved in any database or log file. After processing, the data is automatically cleared from memory. You can safely process sensitive API responses and private data.

The choice of separator depends on your use case:

• . Dot – best for JavaScript object access, Elasticsearch, MongoDB.
• / Slash – ideal for REST API paths, Firebase Realtime DB.
• _ Underscore – perfect for SQL column names, Python variable naming.
• -> Arrow – for PHP associative arrays and readable debugging.

CSV (Comma Separated Values) – compatible with Excel, Google Sheets and almost every data tool. If values contain commas, automatic quote‑escaping is applied. TSV (Tab Separated Values) – when values contain commas and you need a cleaner database import. Values are separated by tab characters, making parsing more reliable.

Max Depth lets you control how many levels are flattened. Example: at depth 2, a.b.c.d will flatten only to a.b, and c.d remains as a raw object value. Use it when you only need the top‑level structure or want to preserve nested arrays. Default: Unlimited – the whole tree is flattened.

ON (Recommended): array indices are included in keys — users.0.name, users.1.name. Each item becomes uniquely addressable – perfect for databases and spreadsheets. OFF: array items are flattened without indices; the last item may override duplicate keys. Use only when the array order does not matter and you just need the values.

In Python you would use pandas.json_normalize() or the flatten_json library – but these require a client environment or server setup. JSON-Slayer’s PHP engine is browser‑based – no installation, no setup. Just paste and Slay. For enterprise use, the PHP engine is more secure and scalable.

Common JSON errors and fixes:

• Trailing commas – there should be no comma after the last item.
• Single quotes – JSON only accepts double quotes ".
• Unquoted keys – {name: "x"} is invalid; {"name": "x"} is correct.
• Comments – // or /* */ are not allowed in JSON.
• First validate your JSON on jsonlint.com and then paste it.

For Excel import:

• Select CSV as the output format.
• Press the Download button – you will get slayed_output.csv.
• Open Excel → Data → From Text/CSV → select the file → Load.

If your values contain commas, download as TSV and import using the Tab delimiter – the data will appear perfectly in columns.

Best approach:

• Flatten the JSON with JSON-Slayer – use the underscore _ separator (SQL‑friendly column names).
• Download as CSV.
• Import using MySQL Workbench or the LOAD DATA INFILE command.

The keys automatically become column names. Pro tip: keep Array Index ON so every row is unique and primary key conflicts are avoided.

Completely free – no account, no signup, no credit card. Just open the page, paste your JSON, and Slay. This is Zlvox’s open‑use tool. You can use it unlimited times – free access for developers, data analysts, and students.