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ZEKILO Dev
ZEKILO Dev
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ZEKILO family

ZEKILO Calculators (zekilo.com)ZEKILO Studio file tools (studio.zekilo.com)
ZEKILO Dev

Developer tools that never leave your browser.

  • Zero Send

    Your input stays in this browser. It is not sent to a server or stored.

  • Instant

    Results appear as you type. No button to press, no round trip.

  • Precise

    Errors come with a line, a column, and a way to fix them.

About ZEKILO Dev and Zero Send

Last updated 2026.10.03

Why we built ZEKILO Dev

Development work means pasting API responses, JWTs, configuration files, and logs into online tools. Those snippets can contain tokens, keys, or customer data, and it is hard to use a tool with confidence when you cannot tell where the pasted text goes. We started ZEKILO Dev to build developer tools that process what you paste only in this browser, without sending it to a server. We call this principle Zero Send.

The tools cover everyday tasks such as formatting and validating JSON, Base64 and URL encoding, decoding JWTs, generating hashes and UUIDs, testing regular expressions, and converting timestamps. The site is available in English, Korean, and Japanese, and it is free to use with no sign-up and nothing to install.

The Zero Send principle

  1. Input is processed only in the browser. The text you type or paste into a tool, the contents of a file you open, and the result are not sent to a server, and they are not put into analytics or the page address (URL).
  2. Input is not stored. Reloading the page clears the input and the result. Only option values such as indentation are kept in the browser for your next visit.
  3. We publish how it works so you can check. How Zero Send Works describes where processing happens, which network requests are made, what is stored, how to verify it yourself, and what the limits are.
  4. Processing follows published standards. Each tool page lists the standards it is based on, together with option descriptions and examples.

How we operate

  1. Accuracy checks — Options, output formats, and error handling are defined in a specification, and the reference cases in that specification are verified by automated tests. Any change to the processing logic must pass the same tests again before it is released.
  2. Automated transmission check — Automated tests type a marker string into the tools and confirm that it appears in none of the requests the browser sends and nowhere in browser storage.
  3. Open library list — The open source libraries we use are pinned to exact versions and listed on the Open Source Licenses page.
  4. Acting on error reports — We review what you send through the error report link on each tool page. When we fix something, we update the reference date and the change history on that page.
  5. Ads kept apart — No ads are placed inside the work card, which holds the input and output areas and the buttons. The about page, the policy and information pages, and the 404 page carry no advertising script. See the Advertising Notice for details.

Before you use the tools

Results are for reference. Check that a result meets your requirements before you use it in production.

Decoding is not signature verification, and Base64 is an encoding, not encryption. For security-related tools, read the notes on each tool page as well.

Zero Send means that the site does not send your input anywhere. It cannot stop what browser extensions or other programs installed on your device do. The scope and the limits are described in How Zero Send Works.

Family sites

ZEKILO Dev is one of the ZEKILO family sites. All three are run by the same operator.

  • ZEKILO Calculators (zekilo.com) — discount, VAT, currency, unit, and date calculators, available in Korean and Japanese
  • ZEKILO Studio (studio.zekilo.com) — file tools that process files in the browser
  • ZEKILO Dev (dev.zekilo.com) — developer tools that process text and code in the browser

Each site has its own privacy policy and terms of use. The documents on this site apply to this site.

Operator

  • Operator: HYUNJUNG S&C (representative: KIM HYUNMIN)

Contact

  • Email: manager@zekilo.com
  • For a tool error, please use the error report link on that tool page. It opens an email draft with the tool ID, the page address, your browser and operating system, and the error code filled in. Your input and the result are not attached automatically.
  • Please do not put real tokens, passwords, or other secrets in the email.

We use your email address and message only to reply and to fix errors. See the Privacy Policy for details.