Why can I not just paste JSON into a URL?

URLs only allow a small set of safe characters. Braces, quotes, colons, spaces and slashes have reserved meanings — a server reading ?data={"a":1} stops at the quote or the space, and the ampersand inside a query string splits the value in two. Percent-encoding turns every unsafe character into a %XX sequence, so the server sees one continuous, unambiguous value.

What is the difference between encodeURIComponent and escape?

encodeURIComponent is the correct function: it encodes every character that is not valid in a URL component, including quotes, braces and ampersands, and it handles UTF-8 correctly for emoji and international text. The legacy escape function mangles non-ASCII characters and should never be used — this tool implements the modern, correct behaviour.

What is the difference between %20 and + in URLs?

Both represent a space. + is the form-encoding convention used by application/x-www-form-urlencoded POST bodies and sometimes query strings; %20 is the pure percent-encoding form. This tool has a plus-mode option so you can produce either variant — use plus mode when the receiver is form-style parsing, default otherwise.

Does encoding break the JSON structure?

No. Percent-encoding is fully reversible — every character is restored exactly on decode. The JSON structure is preserved inside the encoded string; it just becomes unreadable until decoded. Use the companion URL Decoder to bring it back.

How long can the encoded JSON be?

Browser URL limits are practical constraints, not specs: roughly 2,000 characters in older Internet Explorer, about 8,000 in most modern browsers, and far less in some CDNs and proxies. If your JSON exceeds those sizes, prefer base64 or a POST body instead of a URL.

Is my JSON uploaded anywhere?

No. Validation and encoding happen entirely in your browser. Nothing is sent to a server, logged or stored.

JSON URL Encoder

Percent-encode JSON for URL query strings and fragments instantly. Correct encodeURIComponent encoding, plus-mode option, live preview, copy and download.

JSON Input

Encode spaces as + (form-style) Pretty-print JSON before encoding

Waiting for input

URL-Encoded Output

Paste the encoded value after a query parameter, e.g. ?data=... Percent-encoding is reversible — the URL decoder tool restores the original JSON.

About JSON URL Encoder

URLs are stingy about what they accept. Braces, quotes, colons, spaces, ampersands and slashes all carry meaning in a URL, so the moment you try to ship JSON through a query string or fragment — passing state between pages, prefilling a form, sharing a filtered view, embedding config in a widget — the URL breaks: the value truncates at the first ampersand, the server rejects the braces, or the browser sends a malformed request.

The fix is percent-encoding, and the classic mistake is doing it with the wrong function. The legacy escape() function corrupts UTF-8, producing mojibake the receiver cannot repair. JSON URL Encoder implements encodeURIComponent semantics correctly: every reserved character becomes a safe %XX sequence, Unicode content is encoded as proper UTF-8, and you can choose the form-encoding convention (+ for spaces) when the receiver expects it. Validate your JSON, watch the encoded value update live, grab the ready-to-paste query usage, and copy or download — all client-side, nothing uploaded.

Features

Correct encoding: Uses encodeURIComponent semantics — every reserved character encoded, no mangled UTF-8, no legacy escape() corruption.
JSON validation first: Broken documents are flagged before encoding so you never publish a truncated value.
Plus-mode option: Switch %20 to + for receivers that parse form-style query strings.
Optional reformat: Pretty-print the JSON before encoding to keep the round trip readable.
Ready-to-paste usage: An example ?data=... line is generated alongside the encoded value.
Live conversion: The output updates as you type — no convert button required.
Copy and download: Grab the encoded string or save it as a file in one click.
Size visibility: Character counts on both sides show exactly how much the encoding added.

How to Use

Paste your JSON into the input pane. Syntax is validated immediately.
Choose the conventions. Turn on plus mode if the receiver parses form-encoded values; leave it off for standard percent encoding. Reformat on if you want the round trip to be readable.
Watch the output update live — every reserved character becomes a %XX sequence.
Use the usage line to see exactly how the value slots into a query string: ?data=.
Copy or download the encoded value. Note the length: URLs have practical limits around 2,000 to 8,000 characters.

Examples

Example 1 — Sharing a filtered dashboard view. A team wants to share a report with filters applied. The filter JSON {filters:[{field:"region",op:"eq",value:"eu-west"}]} is URL-encoded into the fragment: #view=eyJmaWx0... — the URL stays shareable, and the receiver decodes it back with the URL decoder tool.

Example 2 — Prefilling a form via link. A support page accepts prefilled fields from a campaign link. The defaults JSON is encoded into ?prefill=... and the form reads it on load. Encoding is what keeps the braces and quotes from breaking the URL.

Example 3 — Widget configuration. An embeddable chart widget takes its config as a query parameter. The config JSON goes through this encoder, the widget decodes it, and the