---
seo_title: Data Format Conversion API: JSON, XML, YAML, CSV | EnConvert
meta_desc: Convert JSON, XML, YAML, CSV, TOML, and Markdown with EnConvert's data format REST API. Eleven POST endpoints returning results directly or via presigned URLs.
keywords: data format conversion api, json xml yaml csv converter api, json to xml api, csv to json api, yaml to json api, json to toml api, markdown to html api, structured data conversion api
---

# Data Format Conversion API

The Data Formats endpoints convert structured data files between JSON, XML, YAML, CSV, and TOML, plus render Markdown to fully styled HTML. Each conversion is a single `POST` request with a `multipart/form-data` file upload: send your file, get the converted result back as raw bytes, or request a presigned download URL instead. All eleven endpoints follow the same request shape, authentication, and error model, so integrating a second format after your first takes minutes.

## Supported conversions

| Conversion | Endpoint | Description |
|------------|----------|-------------|
| [JSON to XML](/docs/endpoints/convert/data-formats/json-to-xml.md) | `POST /v1/convert/json-to-xml` | Converts JSON to XML with objects as children of `<root>`, arrays wrapped in `<item>` elements, and scalars in `<value>`. |
| [XML to JSON](/docs/endpoints/convert/data-formats/xml-to-json.md) | `POST /v1/convert/xml-to-json` | Converts XML to JSON, mapping attributes to `@`-prefixed keys, text content to `#text`, and repeated sibling elements to arrays. |
| [JSON to YAML](/docs/endpoints/convert/data-formats/json-to-yaml.md) | `POST /v1/convert/json-to-yaml` | Direct mapping to human-readable block-style YAML with key order and unicode preserved. |
| [YAML to JSON](/docs/endpoints/convert/data-formats/yaml-to-json.md) | `POST /v1/convert/yaml-to-json` | Safely parses `.yaml` or `.yml` files (no arbitrary code execution) into pretty-printed 2-space-indented JSON. |
| [JSON to CSV](/docs/endpoints/convert/data-formats/json-to-csv.md) | `POST /v1/convert/json-to-csv` | Converts a JSON array of objects to comma-delimited CSV with headers taken from the first object's keys. |
| [CSV to JSON](/docs/endpoints/convert/data-formats/csv-to-json.md) | `POST /v1/convert/csv-to-json` | Converts CSV to a JSON array where the header row becomes the keys and every value stays a string (no type inference). |
| [JSON to TOML](/docs/endpoints/convert/data-formats/json-to-toml.md) | `POST /v1/convert/json-to-toml` | Converts JSON to TOML, wrapping arrays under an `items` key and scalars under `value`; `null` values are rejected with a 400. |
| [TOML to JSON](/docs/endpoints/convert/data-formats/toml-to-json.md) | `POST /v1/convert/toml-to-json` | Converts TOML tables and arrays to pretty-printed JSON, serializing datetime values as ISO-8601 strings. |
| [CSV to XML](/docs/endpoints/convert/data-formats/csv-to-xml.md) | `POST /v1/convert/csv-to-xml` | Converts CSV to XML with column headers as element tag names and each row as an `<item>` inside `<root>`. |
| [XML to CSV](/docs/endpoints/convert/data-formats/xml-to-csv.md) | `POST /v1/convert/xml-to-csv` | Flattens tabular XML (repeated sibling elements with consistent fields) into comma-delimited CSV rows. |
| [Markdown to HTML](/docs/endpoints/convert/data-formats/markdown-to-html.md) | `POST /v1/convert/markdown-to-html` | Renders `.md` or `.markdown` files into a complete, self-contained HTML page with embedded CSS, tables, code blocks, TOC support, and dark mode. |

## Shared conventions

- **Authentication:** Every endpoint accepts either a private API key via the `X-API-Key` header or a JWT `Authorization: Bearer` token obtained from a public key. See [Authentication](/docs/authentication.md).
- **Request shape:** All conversions are synchronous `multipart/form-data` POSTs with a required `file` field plus optional `output_filename` and `direct_download` parameters. See [Sync and Async Jobs](/docs/concepts/sync-and-async.md).
- **Responses:** By default (`direct_download=true`) the converted file is returned as raw bytes; with `direct_download=false` you receive JSON metadata containing a `presigned_url`, `object_key`, `filename`, `file_size`, and `conversion_time_seconds`.
- **Input requirements:** All inputs must be UTF-8 encoded and match the expected file extension; maximum file size is plan-dependent (Founding plan: 5 MB).
- **Errors:** Invalid files or failed conversions return `400`, missing or invalid credentials `401`, exceeded plan limits `402`, and oversized files `413`. See [Error Codes](/docs/reference/errors.md).

## Frequently asked questions

### How do I authenticate requests to the data format conversion endpoints?

All eleven endpoints accept either a private API key in the `X-API-Key` header or a JWT `Authorization: Bearer` token obtained from a public key. The same credentials work across every conversion. See [Authentication](/docs/authentication.md) for details.

### Can I get a download URL instead of the converted file bytes?

Yes. Every endpoint returns the converted file as raw bytes by default; set `direct_download=false` to receive JSON metadata with a `presigned_url`, `object_key`, `filename`, `file_size`, and `conversion_time_seconds` instead.

### What file size and input limits apply to data format conversions?

The maximum file size is plan-dependent (Founding plan: 5 MB), and files exceeding your plan's limit return `413 Payload Too Large`. All inputs must be UTF-8 encoded, and each conversion bills one op against your plan's monthly ops allowance, so exhausting it returns `402 Payment Required`.