Convert Kindle (AZW3) to Textile

Turn Kindle (AZW3), Amazon's KF8 Kindle format used by modern Kindle devices, into Textile, a lightweight markup language used by Redmine and older CMSes. FileChanger runs the document conversion in one call, no local tooling to install.

In the browser

Upload a file and download the result, no pipeline required. Open the converter.

One API call

POST the file with from=azw3 and to=textile, get the converted bytes back. Jump to the code.

From an agent

FileChanger ships an MCP server, so agents can run this conversion themselves. See the docs for setup.

Convert Kindle (AZW3) to Textile in code

The same call from any language: POST the file to /api/convert, the response body is the converted file.

curl -X POST https://filechanger.io/api/convert \
  -H "X-Api-Key: fc_your_api_key_here" \
  -F "file=@input.azw3" \
  -F "from=azw3" \
  -F "to=textile" \
  -o output.textile

import requests

with open("input.azw3", "rb") as f:
    response = requests.post(
        "https://filechanger.io/api/convert",
        headers={"X-Api-Key": "fc_your_api_key_here"},
        files={"file": f},
        data={"from": "azw3", "to": "textile"},
    )

response.raise_for_status()
with open("output.textile", "wb") as out:
    out.write(response.content)

const formData = new FormData();
formData.append("file", fileInput.files[0]);
formData.append("from", "azw3");
formData.append("to", "textile");

const response = await fetch("https://filechanger.io/api/convert", {
  method: "POST",
  headers: { "X-Api-Key": "fc_your_api_key_here" },
  body: formData,
});

const output = await response.blob();

import java.net.http.HttpRequest.BodyPublishers;
import java.net.http.HttpResponse.BodyHandlers;
import java.nio.file.Path;

String boundary = "----FormBoundary" + System.currentTimeMillis();
byte[] fileBytes = java.nio.file.Files.readAllBytes(Path.of("input.azw3"));

String body = "--" + boundary + "\r\n"
    + "Content-Disposition: form-data; name=\"file\"; filename=\"input.azw3\"\r\n"
    + "Content-Type: application/octet-stream\r\n\r\n"
    + new String(fileBytes) + "\r\n"
    + "--" + boundary + "\r\nContent-Disposition: form-data; name=\"from\"\r\n\r\nazw3\r\n"
    + "--" + boundary + "\r\nContent-Disposition: form-data; name=\"to\"\r\n\r\ntextile\r\n"
    + "--" + boundary + "--";

HttpClient client = HttpClient.newHttpClient();
HttpRequest request = HttpRequest.newBuilder()
    .uri(URI.create("https://filechanger.io/api/convert"))
    .header("X-Api-Key", "fc_your_api_key_here")
    .header("Content-Type", "multipart/form-data; boundary=" + boundary)
    .POST(BodyPublishers.ofString(body))
    .build();

HttpResponse<byte[]> response = client.send(
    request, BodyHandlers.ofByteArray());
java.nio.file.Files.write(Path.of("output.textile"), response.body());

import Network.HTTP.Client
import Network.HTTP.Client.MultipartFormData
import qualified Data.ByteString.Lazy as BL

main :: IO ()
main = do
  manager <- newManager defaultManagerSettings
  initialReq <- parseRequest "POST https://filechanger.io/api/convert"
  let req = initialReq
        { requestHeaders = [("X-Api-Key", "fc_your_api_key_here")] }
  request <- formDataBody
    [ partFileSource "file" "input.azw3"
    , partBS "from" "azw3"
    , partBS "to" "textile"
    ] req

  response <- httpLbs request manager
  BL.writeFile "output.textile" (responseBody response)

About Textile

Textile is a lightweight markup language that predates Markdown, still used by Redmine and a number of older content management systems. Teams maintaining or migrating legacy Redmine wikis and CMS content are its main users today.

Frequently asked questions

How do I convert Kindle (AZW3) to Textile?

Upload your file in the browser converter and pick Textile as the target, or POST it to /api/convert with from=azw3 and to=textile. The response body is the converted file.

Is converting Kindle (AZW3) to Textile free?

Yes. The free tier includes 2 GB of conversions per month, metered on input size. See pricing for the paid tiers.

Is there an API for Kindle (AZW3) to Textile conversion?

Yes, this whole conversion is one POST to /api/convert (the code examples above show it in five languages), plus an MCP server so AI agents can run it directly.