Base64 Encode / Decode
Encode strings to Base64 and decode Base64 back to plain text. Supports standard and URL-safe (base64url) variants.
Overview
Use Cases
- Encode binary data for safe transmission in JSON or HTML
- Decode Base64 payloads from third-party APIs or webhooks
- Build developer tools and data inspection utilities
- URL-safe encoding for tokens in URLs and filenames
- Encoding credentials for Basic Auth headers
Features
Standard Base64 encoding and decoding (RFC 4648)
URL-safe Base64 encoding and decoding (base64url, RFC 4648 Β§5)
Returns 422 with a clear error for invalid Base64 input
Zero dependencies β fast, in-memory only
API Endpoints
Encode
Encode a plain-text string to Base64
POST
https://api.requiems.xyz/v1/convert/base64/encode
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
| value | string |
Required | The string to encode |
| variant | string |
Optional | Encoding variant: standard (default) or url (URL-safe base64url) |
Try it out
Live DemoRequest
The string to encode
Encoding variant: standard (default) or url (URL-safe base64url)
Sending request...
Response Fields
| Field | Type | Description |
|---|---|---|
| result | string |
The Base64-encoded output |
Code Examples
curl -X POST https://api.requiems.xyz/v1/convert/base64/encode \
-H "requiems-api-key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"value": "Hello, world!"}'
# URL-safe variant
curl -X POST https://api.requiems.xyz/v1/convert/base64/encode \
-H "requiems-api-key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"value": "Hello, world!", "variant": "url"}'import requests
url = "https://api.requiems.xyz/v1/convert/base64/encode"
headers = {"requiems-api-key": "YOUR_API_KEY"}
payload = {"value": "Hello, world!"}
response = requests.post(url, json=payload, headers=headers)
print(response.json()["data"]["result"]) # SGVsbG8sIHdvcmxkIQ==const response = await fetch('https://api.requiems.xyz/v1/convert/base64/encode', {
method: 'POST',
headers: {
'requiems-api-key': 'YOUR_API_KEY',
'Content-Type': 'application/json'
},
body: JSON.stringify({ value: 'Hello, world!' })
});
const { data } = await response.json();
console.log(data.result); // SGVsbG8sIHdvcmxkIQ==require 'net/http'
require 'json'
uri = URI('https://api.requiems.xyz/v1/convert/base64/encode')
request = Net::HTTP::Post.new(uri)
request['requiems-api-key'] = 'YOUR_API_KEY'
request['Content-Type'] = 'application/json'
request.body = { value: 'Hello, world!' }.to_json
response = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) do |http|
http.request(request)
end
puts JSON.parse(response.body)['data']['result'] # SGVsbG8sIHdvcmxkIQ==Error Responses
400
bad_request
Missing or empty value field
422
validation_failed
Validation constraint on the variant field (must be standard or url)
Decode
Decode a Base64-encoded string back to plain text
POST
https://api.requiems.xyz/v1/convert/base64/decode
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
| value | string |
Required | The Base64-encoded string to decode |
| variant | string |
Optional | Encoding variant: standard (default) or url (URL-safe base64url) |
Try it out
Live DemoRequest
The Base64-encoded string to decode
Encoding variant: standard (default) or url (URL-safe base64url)
Sending request...
Response Fields
| Field | Type | Description |
|---|---|---|
| result | string |
The decoded plain-text output |
Code Examples
curl -X POST https://api.requiems.xyz/v1/convert/base64/decode \
-H "requiems-api-key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"value": "SGVsbG8sIHdvcmxkIQ=="}'
# URL-safe variant
curl -X POST https://api.requiems.xyz/v1/convert/base64/decode \
-H "requiems-api-key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"value": "SGVsbG8sIHdvcmxkIQ==", "variant": "url"}'import requests
url = "https://api.requiems.xyz/v1/convert/base64/decode"
headers = {"requiems-api-key": "YOUR_API_KEY"}
payload = {"value": "SGVsbG8sIHdvcmxkIQ=="}
response = requests.post(url, json=payload, headers=headers)
result = response.json()
if response.status_code == 200:
print(result["data"]["result"]) # Hello, world!
else:
print(f"Error: {result['error']}") # invalid_base64const response = await fetch('https://api.requiems.xyz/v1/convert/base64/decode', {
method: 'POST',
headers: {
'requiems-api-key': 'YOUR_API_KEY',
'Content-Type': 'application/json'
},
body: JSON.stringify({ value: 'SGVsbG8sIHdvcmxkIQ==' })
});
if (response.ok) {
const { data } = await response.json();
console.log(data.result); // Hello, world!
} else {
const err = await response.json();
console.error(err.error); // invalid_base64
}require 'net/http'
require 'json'
uri = URI('https://api.requiems.xyz/v1/convert/base64/decode')
request = Net::HTTP::Post.new(uri)
request['requiems-api-key'] = 'YOUR_API_KEY'
request['Content-Type'] = 'application/json'
request.body = { value: 'SGVsbG8sIHdvcmxkIQ==' }.to_json
response = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) do |http|
http.request(request)
end
body = JSON.parse(response.body)
if response.code == '200'
puts body['data']['result'] # Hello, world!
else
puts body['error'] # invalid_base64
endError Responses
400
bad_request
Missing or empty value field
422
invalid_base64
The value is not valid Base64 and cannot be decoded
Frequently Asked Questions
Standard Base64 uses the alphabet A-Z, a-z, 0-9, +, and /. The url variant (base64url) replaces + with - and / with _ so the output is safe to include directly in URLs and filenames without percent-encoding.
No. Both the standard and url variants use strict Base64 decoding which requires correct = padding. If your input lacks padding, add the appropriate number of = characters before decoding. A 422 invalid_base64 error is returned for malformed or unpadded input.
The endpoint accepts a JSON string. If your binary data can be represented as a UTF-8 string you can pass it directly. For raw binary (non-UTF-8 bytes), encode it on the client side before sending.
Yes. The entire JSON request body is capped at 1 MB (the platform-wide limit for all POST endpoints). Because Base64 encoding increases payload size by roughly 33%, input strings should be kept well under 750 KB to stay within that limit.