AltF Flow recipe

Decode Base64 and pretty print JSON

To read JSON that arrives Base64-encoded, decode it to text and then format it. This recipe ignores line breaks and spaces in the encoded string, accepts both standard Base64 and the URL-safe - and _ variant, decodes the bytes as UTF-8 and pretty prints the JSON with two-space indentation. If the decoded text is not JSON, the second step stops with an error.

  • Free, no sign-up
  • Runs in your browser
  • Nothing uploaded
  • Share recipes as a link

2 steps · runs in your browser · nothing uploaded

Pipeline

  1. Base64 decode

    5 → 1 lines (-4)

  2. Pretty-print JSON with indentation, optionally sorting keys.

    1 → 21 lines (+20)

5lines5words284chars

21lines35words333chars+16 lines vs input

The 2 steps in this recipe

  1. 1

    Encode or decode - Base64 decode

    URL, Base64, HTML entity and JSON string encoding, both directions.

  2. 2

    Format JSON

    Pretty-print JSON with indentation, optionally sorting keys.

Change any option in the workspace above, switch a step off to compare, or add your own steps. Save it to reuse it, or share the recipe as a link.

Worked example

Before
eyJldmVudCI6Im9yZGVyLmNyZWF0ZWQiLCJpZCI6ImV2dF8wMDAxIiwiZGF0
YSI6eyJvcmRlcl9pZCI6IkEtMTA0MiIsImN1c3RvbWVyIjoiVGVzdCBDdXN0
b21lciIsIml0ZW1zIjpbeyJza3UiOiJTS1UtUkVELTAxIiwicXR5IjoyfSx7
InNrdSI6IlNLVS1CTFUtMDciLCJxdHkiOjF9XSwidG90YWwiOjQ4LjUsImN1
cnJlbmN5IjoiVVNEIn0sInNhbmRib3giOnRydWV9
After
{
  "event": "order.created",
  "id": "evt_0001",
  "data": {
    "order_id": "A-1042",
    "customer": "Test Customer",
    "items": [
      {
        "sku": "SKU-RED-01",
        "qty": 2
      },
      {
        "sku": "SKU-BLU-07",
        "qty": 1
      }
    ],
    "total": 48.5,
    "currency": "USD"
  },
  "sandbox": true
}

Why two steps

Decoding gives you the JSON as one long line. Formatting it adds indentation and line breaks so nested objects and arrays are readable. Keeping them as separate steps also tells you where a problem is: an error on step 1 means the Base64 is broken, an error on step 2 means the decoded text is not valid JSON.

Variations

  • Turn on Sort keys A-Z in the format step to compare two payloads field by field.
  • Add Minify JSON instead of Format JSON to get compact output for a test fixture.
  • For a JWT, paste only the middle segment between the dots; signatures are not verified.

Base64 to pretty JSON: questions and answers

Does it handle Base64url without padding?

Yes. - and _ are mapped back to + and /, and missing = padding is accepted.

What if the payload is not JSON?

The run stops at step 2 and the output shows the decoded text from step 1, so you can still read it.

Is the payload sent anywhere?

No. Decoding happens in your browser, which matters when payloads contain customer data or tokens.

More recipes like this

Developers and data

List to SQL IN clauseTurn a pasted column of IDs or codes into a SQL IN (...) list: trimmed, deduped, single-quoted with apostrophes escaped and joined with commas.
  1. Trim every line
  2. Remove empty lines
  3. Remove duplicate lines
  4. Quote each line
  5. +2 more
CSV to JSON with cleanupTrim stray spaces around CSV values and drop blank rows before converting to a JSON array of objects keyed by the header row. Runs locally.
  1. Trim whitespace
  2. Remove empty lines
  3. Trim every line
  4. Find and replace
  5. +1 more
JSON to CSV, sorted columnsConvert a JSON array of objects to CSV with a header row, sorting keys first so columns come out in a predictable A-Z order. Free, no upload.
  1. Format JSON
  2. JSON to CSV
Filter errors from a logKeep only ERROR and FATAL log lines, strip timestamps, mask numbers and dedupe, so a long log shrinks to the distinct errors that happened.
  1. Filter lines
  2. Find and replace
  3. Find and replace
  4. Remove duplicate lines
Wrap text at 72 charactersTrim a commit message or plain-text email, squeeze extra blank lines to one and hard wrap every paragraph at 72 characters on word boundaries.
  1. Trim whitespace
  2. Remove empty lines
  3. Wrap at a width
See all 22 recipes

Every step you can add (41)

Clean up

  • Trim whitespace
  • Trim every line
  • Remove empty lines
  • Collapse repeated spaces
  • Remove line breaks
  • Strip HTML tags
  • Straighten smart quotes
  • Remove accents
  • Remove punctuation
  • Remove emoji
  • Remove non-ASCII characters

Change case

  • Change case
  • Make URL slugs

Lines

  • Sort lines
  • Remove duplicate lines
  • Keep only duplicated lines
  • Compare with another list
  • Count repeated lines
  • Reverse line order
  • Shuffle lines
  • Keep a range of lines
  • Truncate long lines
  • Wrap at a width
  • Split into lines
  • Join lines

Find and filter

  • Find and replace
  • Filter lines
  • Remove words or characters

Extract

  • Extract

Data and formats

  • Format JSON
  • Minify JSON
  • CSV to JSON
  • JSON to CSV
  • Lines to JSON array
  • JSON array to lines

Encode and decode

  • Encode or decode

Build output

  • Add prefix / suffix
  • Quote each line
  • Number lines
  • Apply a line template
  • Add timestamp
What each step does, with its options

AltF Flow runs entirely in your browser. Your text is never sent to AltFTool; saved recipes stay in this browser and shared links carry the steps only.