Convert EPUB to MD API

Convert EPUB to MD in three requests

Authenticate with a bearer key from your backend (never ship the key to the browser). Submit the conversion, upload the file to the presigned URL, poll until it is done, and download the result.

curl

# 1. Submit the conversion
curl -X POST https://hushvert.com/api/v1/conversions \
  -H "Authorization: Bearer $HUSHVERT_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $(uuidgen)" \
  -d '{ "pair": "epub-to-md", "bytes": '$(wc -c < input.epub)' }'
# -> { "jobId": "...", "uploadUrl": "...", "pollUrl": "/api/v1/conversions/..." }

# 2. Upload the file to the presigned uploadUrl
curl -X PUT "$UPLOAD_URL" --data-binary @input.epub

# 3. Poll until done, then download
curl https://hushvert.com/api/v1/conversions/$JOB_ID \
  -H "Authorization: Bearer $HUSHVERT_KEY"
# -> { "status": "done", "downloadUrl": "...", "expiresAt": "..." }
curl -o output.md "$DOWNLOAD_URL"

Node.js

import { readFile, writeFile } from 'node:fs/promises'

const KEY = process.env.HUSHVERT_KEY
const bytes = await readFile('input.epub')

// 1. Submit
const submit = await fetch('https://hushvert.com/api/v1/conversions', {
  method: 'POST',
  headers: { authorization: `Bearer ${KEY}`, 'content-type': 'application/json' },
  body: JSON.stringify({ pair: 'epub-to-md', bytes: bytes.byteLength }),
}).then((r) => r.json())

// 2. Upload to the presigned URL
await fetch(submit.uploadUrl, { method: 'PUT', body: bytes })

// 3. Poll until done
let job
do {
  await new Promise((r) => setTimeout(r, 1500))
  job = await fetch(`https://hushvert.com${submit.pollUrl}`, {
    headers: { authorization: `Bearer ${KEY}` },
  }).then((r) => r.json())
} while (job.status !== 'done' && job.status !== 'failed')

// 4. Download
const out = await fetch(job.downloadUrl).then((r) => r.arrayBuffer())
await writeFile('output.md', Buffer.from(out))

Python

import os, time, requests

KEY = os.environ["HUSHVERT_KEY"]
data = open("input.epub", "rb").read()

# 1. Submit
submit = requests.post("https://hushvert.com/api/v1/conversions",
    headers={"Authorization": f"Bearer {KEY}"},
    json={"pair": "epub-to-md", "bytes": len(data)}).json()

# 2. Upload to the presigned URL
requests.put(submit["uploadUrl"], data=data)

# 3. Poll until done
job = {}
while job.get("status") not in ("done", "failed"):
    time.sleep(1.5)
    job = requests.get(f"https://hushvert.com{submit['pollUrl']}",
        headers={"Authorization": f"Bearer {KEY}"}).json()

# 4. Download
out = requests.get(job["downloadUrl"]).content
open("output.md", "wb").write(out)

Limits and pricing

Free per month	50 conversions per account, then pay per use from account credits.
Max file size	50 MB
Privacy	Input deleted the moment the conversion finishes; output kept about an hour, then deleted.

See the full request, error codes, and idempotency reference on the API keys page, and the plans on pricing.

Why an API for this?

Document interchange between markup formats needs pandoc and, for some targets, a LaTeX toolchain. The API keeps that toolchain installed and current so you call one endpoint instead of shipping it.

Everything a browser can do (images, HEIC, audio, archives, PDF page operations) runs free and on-device in the open-source @hushvert/engine SDK - no upload, no key. This API is only for EPUB to MD and the other server-only formats.

What is EPUB?

EPUB is the open ebook standard: a zip of HTML, CSS and metadata that reflows to fit any screen, from phones to dedicated e-readers. Unlike a PDF it has no fixed page, so the reader chooses the font and size and the text rewraps. Nearly every reading app outside the Kindle walled garden opens it.

What is MD?

MD (Markdown) is the plain-text writing format of the developer world: headings, lists, links and emphasis expressed with punctuation, readable raw, and rendered everywhere from GitHub to note-taking apps. Because it is just text, it diffs, versions and edits beautifully. Its weakness is the handoff: the moment a reader expects a Word document, markdown needs converting.

EPUB to MD API FAQ

How do I convert EPUB to MD with an API?

Send a POST to /api/v1/conversions with the pair and the byte count, upload the file to the presigned URL it returns, then poll until the job is done and download the result. It is three short requests; full code is above in curl, Node, and Python.

Why not just convert EPUB to MD myself?

You can, if you want to run and maintain pandoc with the matching readers and writers (and sometimes a LaTeX stack). Document interchange between markup formats needs pandoc and, for some targets, a LaTeX toolchain. The API keeps that toolchain installed and current so you call one endpoint instead of shipping it.

What does it cost?

Every account gets 50 free conversions per month across all of its keys. Beyond that, the API draws on account credits, billed per conversion. Everything a browser can do is free and keyless in the open-source SDK.

What happens to my file?

The file uploads over an encrypted connection. The input is deleted the moment the conversion finishes; the converted output is kept for about an hour so you can download it, then deleted too.

Can my AI agent do this conversion?

Yes. The @hushvert/mcp Model Context Protocol server gives Claude Code, Cursor, and other agents a convert_file tool over this same API, so an agent can run the conversion in one call.

EPUB to MD conversion API