JPKCom DB

Coder

Encode and decode HTML entities, URLs, Base64, JSON, JWT, and Data URIs — seven tabs, all client-side in the browser, no account.

Seven encode/decode tools in one place

Web development throws the same small chores at you again and again: quickly escape a chunk of HTML so the angle brackets stay as text. Encode a query parameter correctly for a URL. Figure out what's inside a Base64 string. Or take a JWT and see what its payload claims. For each of these there are one-liners, command-line tricks, or sketchy online converters — and with tokens, that last option is risky.

The Coder bundles these chores into one tool with seven tabs. You pick the right tab, paste your text, click Encode or Decode — done. Everything happens right in your browser: no account, no upload, no installation.

The tool is built for everyone who works with code and data: developers who translate between HTML, URLs, and Base64 all day; backend and API people who want to inspect a JWT without handing it to someone else's server; and anyone who needs to quickly embed an image as a Data URI in their CSS or HTML.

The codecs at a glance

The interface is in English — the tabs are named exactly as shown here in parentheses. The seven functions group into three blocks:

Markup and web

  • HTML entities, basic (HTML tab) — turns &, <, and > into HTML entities and back. The minimum needed to display a code snippet without the browser interpreting it as markup.
  • HTML entities, advanced (HTML+ tab) — same as above, plus double quote " (&quot;) and apostrophe ' (&#39;). You need this when the text lands inside an attribute value.
  • URL encoding (URL tab) — encodes a string for safe use in URLs (built on encodeURIComponent) and decodes it again.

Binary and transport

  • Base64 (Base64 tab) — encodes text to Base64 and back, UTF-8 safe (including accents and emoji). Invalid Base64 input is detected and reported on decode.
  • Data URI (Data URI tab) — converts any file into a Base64-encoded data: URI you can embed directly in CSS or HTML. With a progress indicator and file info.

Data and tokens

  • JSON string (JSON tab) — escapes special characters such as \n, \t, \" to their JSON escape sequences (Escape) and reverses that (Unescape).
  • JWT decoder (JWT tab) — splits a JSON Web Token into header, payload, and signature, and shows the header and payload as formatted JSON. Important: the tool decodes and displays only — it does not verify the signature and does not generate tokens. More on that in the manual.

Everything runs in the browser

The Coder is a pure client-side tool. The server only delivers the page; the actual encoding and decoding is done by JavaScript locally in your browser. There is no server-side processing of your input.

That's not just fast — it's a real privacy advantage: a JWT you decode, a file you turn into a Data URI, a string you Base64-encode — none of it leaves your machine or gets sent to a server. Tokens in particular often carry sensitive claims; here they stay local.

Try it now

→ Open the Coder — pick a tab, paste your text, click Encode or Decode. No account, free, right in the browser.

When the Coder hits its limits, these tools take over:

  • Convertor PRO — converts between HTML/XML, Unicode, UTF-8, hexadecimal, YAML, JSON, and TOML. The bigger sibling for format conversions beyond the plain encode/decode tabs.
  • JSON Editor — format, validate, and transform JSON. Ideal for taking a decoded JWT payload or an unescaped JSON string further.
  • Generator — generate passwords, BCrypt/Argon2 hashes, TOTP codes, and more — the security side next to the JWT tab.

There's more on the subpages: the manual with every tab in detail, hands-on examples, and a collection of tips & tricks.