TASK

Decode nested URL-encoded parameters (Base64 JSON in a query string)

Unwrap the common API pattern where a URL parameter carries URL-encoded Base64 JSON — one chain, three tools, zero copy-pasting between pages.

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APIs often transport structured data through URLs like ?data=eyJhIjoxfQ%3D%3D. Reading it requires unwrapping layers in reverse order: first percent-decoding, then Base64 decoding, then JSON formatting. Doing this by hand across three pages is where mistakes creep in — run it as one chain instead.
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URL Decoder →
Single-layer case: paste just the encoded value and get the decoded text.
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url-decode → base64-decode → json-format
View recipe Open in Toolchain

Paste the full encoded parameter value as the chain input. Each intermediate output is visible, so if a layer fails you see exactly which one and why.
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If the decoded Base64 payload is not JSON but another encoding (e.g. another Base64 layer or percent-encoding inside), extend the chain with the matching tool — the pipeline accepts any order and you can re-run from any node after adjusting it.

Frequently asked questions

Why does %3D appear at the end of the value?: %3D is the percent-encoding of '=' — the Base64 padding character. URL-decode restores it before the Base64 layer runs.
Can I encode in the reverse direction?: Yes — reorder the chain with the encode tools (json → base64-encode → url-encode) using the same builder. Save it as a workflow so the reverse task is one click next time.

Workflows that solve this

Encode a JSON payload for URL transport

Prepare a JSON document for a URL parameter: pretty-print, Base64-encode, then percent-encode — the exact inverse of the nested-parameter decode chain.

Decode nested URL parameter (Base64 JSON)

Unwrap a URL parameter that carries URL-encoded Base64 JSON into readable, formatted JSON.

Base64 encode then decode round-trip

Encode text to Base64 and decode it back to verify the round-trip preserves the original data.

Convert Base64 to Base85

Decode Base64 and re-encode as Base85 for compact representation.

Convert Base64 to Hex

Decode a Base64 string into raw bytes and re-encode it as hexadecimal for inspection or interop.

Compare two YAML configs via JSON

Convert YAML configs to JSON for diff-friendly comparison of structured values.

Decode a Basic Auth credential pair

Decode the Base64 portion of an HTTP Basic Authorization header into username:password.

HJSON to JSON Format

Format HJSON then convert to standard JSON.

Format JSON and compute integrity checksum

Pretty-print a JSON document and compute a CRC32 checksum to detect any subsequent modifications.

Minify and validate JSON

Format JSON for inspection and validate it is syntactically correct in one pass.

Format JSON and generate TypeScript interface

Format a JSON document then infer a TypeScript interface definition in one chain.

Validate, format, then convert JSON to YAML

Convert a (possibly minified) JSON config to YAML, catching syntax errors at the first node instead of producing subtly wrong YAML.

JSON5 to JSON Format

Format JSON5 then convert to standard JSON.

JSONC to JSON Format

Format JSONC (JSON with comments) then convert to standard JSON.

Decode and format a JWT payload

Parse a JWT token, extract its payload, and format the JSON for inspection.

Parse Query String and Format JSON

Parse query string into key-value pairs then format as JSON.

Convert TOML to JSON

Parse a TOML configuration file into JSON for tools and APIs that expect JSON input.

Convert TOML to YAML via JSON

Transform a TOML configuration file into YAML format, using JSON as an intermediate representation.

Decode URL and show hex bytes

Percent-decode a URL-encoded string then view its hexadecimal byte representation for low-level analysis.

URL Decode and Parse

URL-decode then parse the URL into components.

URL double decode

Decode a URL-encoded string that has been encoded twice, recovering the original plaintext.

Generate TypeScript interfaces from YAML

Convert a YAML document to TypeScript interface definitions, using JSON as an intermediate format.

Learn more

Want to understand why?

How to Implement OAuth 2.0 PKCE Flow

Implement the Proof Key for Code Exchange (PKCE) extension to OAuth 2.0 Authorization Code flow for secure public client authentication.

How to Parse Query Strings

A beginner-level guide covering query-string, url, parsing. Includes step-by-step instructions, common errors, troubleshooting tips, and security considerations for query-string.

Form encoding (application/x-www-form-urlencoded) is how HTML forms encode key-value pairs on submission, encoding spaces as + instead of %20.

Percent-Encoding

Percent-encoding is the mechanism that converts unsafe characters in URLs into %HH form, defined by RFC 3986.

Related tools

Decode percent-encoded URL text back to readable characters. Free, private, and 100% client-side.

Decode Base64 data back to readable text online. Free, private, and 100% client-side.

Format, minify, or sort JSON online. Free, private, and 100% client-side.