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JSON to CSV API#

Convert a JSON file to CSV with a single request to POST /v1/convert/json-to-csv. The input must be a JSON array of objects; column headers are derived from the first object's keys, and rows are comma-delimited with QUOTE_MINIMAL quoting. By default the response is raw CSV bytes; set direct_download=false to receive metadata with a presigned download URL instead.

Endpoint#

POST /v1/convert/json-to-csv

Content-Type: multipart/form-data

Accepted input: .json files (UTF-8 encoded)

Output format: .csv (text/csv)

Authentication#

Requires either a private API key or a JWT token from a public key.

X-API-Key: sk_your_private_key

Or:

Authorization: Bearer <jwt_token>

Request Parameters#

Parameter	Type	Required	Default	Description
`file`	file	Yes	--	The `.json` file to convert. Must contain a JSON array of objects. UTF-8 encoded.
`output_filename`	`string`	No	Input filename	Custom output filename. The `.csv` extension is added automatically.
`direct_download`	`boolean`	No	`true`	When `true`, returns raw CSV bytes. When `false`, returns metadata with a presigned download URL.

Conversion Rules#

[
  {"name": "Alice", "age": 30, "city": "London"},
  {"name": "Bob", "age": 25, "city": "Paris"}
]

Becomes:

name,age,city
Alice,30,London
Bob,25,Paris

Input must be a JSON array of objects (list of dictionaries)
Column headers are derived from the first object's keys only
Delimiter is comma (not configurable)
Quoting follows QUOTE_MINIMAL -- values containing commas, quotes, or newlines are quoted
Nested objects or arrays in values are serialized as their string representation (not flattened)

Important: If objects in the array have different keys, extra keys in later objects are silently dropped. Missing keys produce empty values. For best results, ensure all objects have the same set of keys.

Response#

Direct Download (`direct_download=true`, default)#

HTTP 200 OK
Content-Type: text/csv
Content-Disposition: inline; filename="data_20260405_123456789.csv"

Metadata Response (`direct_download=false`)#

{
    "presigned_url": "https://spaces.example.com/...",
    "object_key": "env/files/{project_id}/json-to-csv/data_20260405_123456789.csv",
    "filename": "data_20260405_123456789.csv",
    "file_size": 1234,
    "conversion_time_seconds": 0.03
}

Code Examples#

Python#

import requests

with open("data.json", "rb") as f:
    response = requests.post(
        "https://api.enconvert.com/v1/convert/json-to-csv",
        headers={"X-API-Key": "sk_your_private_key"},
        files={"file": ("data.json", f, "application/json")}
    )

with open("data.csv", "wb") as out:
    out.write(response.content)

Node.js#

const form = new FormData();
form.append("file", fs.createReadStream("data.json"));

const response = await fetch("https://api.enconvert.com/v1/convert/json-to-csv", {
    method: "POST",
    headers: { "X-API-Key": "sk_your_private_key" },
    body: form
});

const csv = await response.text();

PHP#

$ch = curl_init("https://api.enconvert.com/v1/convert/json-to-csv");
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => ["X-API-Key: sk_your_private_key"],
    CURLOPT_POSTFIELDS => ["file" => new CURLFile("data.json", "application/json")]
]);
$csv = curl_exec($ch);
curl_close($ch);

Go#

body := &bytes.Buffer{}
writer := multipart.NewWriter(body)
part, _ := writer.CreateFormFile("file", "data.json")
file, _ := os.Open("data.json")
io.Copy(part, file)
writer.Close()

req, _ := http.NewRequest("POST", "https://api.enconvert.com/v1/convert/json-to-csv", body)
req.Header.Set("Content-Type", writer.FormDataContentType())
req.Header.Set("X-API-Key", "sk_your_private_key")
resp, _ := http.DefaultClient.Do(req)

Error Responses#

Status	Condition
`400 Bad Request`	File is not a `.json` file
`400 Bad Request`	Invalid JSON content
`400 Bad Request`	JSON must be an array of objects for CSV conversion
`400 Bad Request`	JSON array is empty
`400 Bad Request`	JSON array must contain objects (dictionaries)
`401 Unauthorized`	Missing or invalid API key / JWT token
`402 Payment Required`	Monthly ops allowance exhausted
`413 Payload Too Large`	File exceeds plan's maximum file size

Limits#

Limit	Value
Max file size	Plan-dependent (Founding: 5 MB)
Input encoding	UTF-8 only
Input structure	Array of objects only
Monthly conversions	Plan-dependent

Frequently asked questions#

How do I convert a JSON array to CSV with a REST API?#

Send a multipart/form-data POST request to /v1/convert/json-to-csv with a .json file containing an array of objects in the file field, authenticated with an X-API-Key header or a JWT Authorization: Bearer token. The response is comma-delimited CSV.

What happens if the JSON objects have different keys?#

Column headers come from the first object's keys only. Extra keys in later objects are silently dropped and missing keys produce empty values, so ensure all objects share the same key set for best results.

Are nested JSON objects flattened into CSV columns?#

No. Nested objects or arrays in values are serialized as their string representation rather than flattened into separate columns.

Can I change the CSV delimiter?#

No. The delimiter is always a comma and is not configurable. Quoting follows QUOTE_MINIMAL, so values containing commas, quotes, or newlines are quoted automatically.

Why does the JSON to CSV API return 400 Bad Request?#

A 400 is returned when the file is not .json, the JSON is invalid, the JSON is not an array of objects, or the array is empty. Oversized files return 413 Payload Too Large.

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API Documentation