diff --git a/resources/rapydscript/compiler.js.xz b/resources/rapydscript/compiler.js.xz
index 6a76a11b76..9c504c7333 100644
Binary files a/resources/rapydscript/compiler.js.xz and b/resources/rapydscript/compiler.js.xz differ
diff --git a/resources/rapydscript/lib/encodings.pyj b/resources/rapydscript/lib/encodings.pyj
index cd8da7041a..d72e9b54f6 100644
--- a/resources/rapydscript/lib/encodings.pyj
+++ b/resources/rapydscript/lib/encodings.pyj
@@ -1,26 +1,28 @@
 # vim:fileencoding=utf-8
 # License: BSD Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 
-def base64encode(bytes):
+def base64encode(bytes, altchars, pad_char):
     # Convert an array of bytes into a base-64 encoded string
     l = bytes.length
     remainder = l % 3
     main_length = l - remainder
-    encodings = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
+    encodings = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789' + (altchars or '+/')
+    pad_char = '=' if pad_char is undefined else pad_char
     ans = v'[]'
     for v'var i = 0; i < main_length; i += 3':
         chunk = (bytes[i] << 16) | (bytes[i + 1] << 8) | bytes[i + 2]
         ans.push(encodings[(chunk & 16515072) >> 18], encodings[(chunk & 258048) >> 12], encodings[(chunk & 4032) >> 6], encodings[chunk & 63])
     if remainder is 1:
         chunk = bytes[main_length]
-        ans.push(encodings[(chunk & 252) >> 2], encodings[(chunk & 3) << 4], '=', '=')
+        ans.push(encodings[(chunk & 252) >> 2], encodings[(chunk & 3) << 4], pad_char, pad_char)
     elif remainder is 2:
         chunk = (bytes[main_length] << 8) | bytes[main_length + 1]
-        ans.push(encodings[(chunk & 64512) >> 10], encodings[(chunk & 1008) >> 4], encodings[(chunk & 15) << 2], '=')
+        ans.push(encodings[(chunk & 64512) >> 10], encodings[(chunk & 1008) >> 4], encodings[(chunk & 15) << 2], pad_char)
     return ans.join('')
 
 def base64decode(string):
-    # convert the output of base64encode back into an array of bytes (Uint8Array)
+    # convert the output of base64encode back into an array of bytes
+    # (Uint8Array) only works with the standard altchars and pad_char
     if jstype(window) is not 'undefined':
         chars = window.atob(string)
     else:
@@ -30,6 +32,13 @@ def base64decode(string):
         ans[i] = chars.charCodeAt(i)
     return ans
 
+def urlsafe_b64encode(bytes, pad_char):
+    return base64encode(bytes, '-_', pad_char)
+
+def urlsafe_b64decode(string):
+    string = String.prototype.replace.call(string, /[_-]/g, def(m): return '+' if m is '-' else '/';)
+    return base64decode(string)
+
 def hexlify(bytes):
     ans = v'[]'
     for v'var i = 0; i < bytes.length; i++':
diff --git a/resources/rapydscript/lib/uuid.pyj b/resources/rapydscript/lib/uuid.pyj
new file mode 100644
index 0000000000..ad69d1e085
--- /dev/null
+++ b/resources/rapydscript/lib/uuid.pyj
@@ -0,0 +1,77 @@
+# vim:fileencoding=utf-8
+# License: BSD Copyright: 2017, Kovid Goyal <kovid at kovidgoyal.net>
+# globals: crypto
+from __python__ import hash_literals
+
+from encodings import hexlify, urlsafe_b64decode, urlsafe_b64encode
+
+RFC_4122 = 1
+
+if jstype(crypto) is 'object' and crypto.getRandomValues:
+    random_bytes = def (num):
+        ans = Uint8Array(num or 16)
+        crypto.getRandomValues(ans)
+        return ans
+else:
+    random_bytes = def (num):
+        ans = Uint8Array(num or 16)
+        for i in range(ans.length):
+            ans[i] = Math.floor(Math.random() * 256)
+        return ans
+
+
+def uuid4_bytes():
+    data = random_bytes()
+    data[6] = 0b01000000 | (data[6] & 0b1111)
+    data[8] = (((data[8] >> 4) & 0b11 | 0b1000) << 4) | (data[8] & 0b1111)
+    return data
+
+
+def as_str():
+    h = this.hex
+    return h[:8] + '-' + h[8:12] + '-' + h[12:16] + '-' + h[16:20] + '-' + h[20:]
+
+
+def uuid4():
+    b = uuid4_bytes()
+    return {
+        'hex': hexlify(b),
+        'bytes': b,
+        'variant': RFC_4122,
+        'version': 4,
+        '__str__': as_str,
+        'toString': as_str,
+    }
+
+
+def num_to_string(numbers, alphabet, pad_to_length):
+    ans = v'[]'
+    alphabet_len = alphabet.length
+    numbers = Array.prototype.slice.call(numbers)
+    for v'var i = 0; i < numbers.length - 1; i++':
+        x = divmod(numbers[i], alphabet_len)
+        numbers[i] = x[0]
+        numbers[i+1] += x[1]
+    for v'var i = 0; i < numbers.length; i++':
+        number = numbers[i]
+        while number:
+            x = divmod(number, alphabet_len)
+            number = x[0]
+            ans.push(alphabet[x[1]])
+    if pad_to_length and pad_to_length > ans.length:
+        ans.push(alphabet[0].repeat(pad_to_length - ans.length))
+    return ans.join('')
+
+
+def short_uuid():
+    # A totally random uuid encoded using only URL and filename safe characters
+    return urlsafe_b64encode(random_bytes(), '')
+
+
+def short_uuid4():
+    # A uuid4 encoded using only URL and filename safe characters
+    return urlsafe_b64encode(uuid4_bytes(), '')
+
+
+def decode_short_uuid(val):
+    return urlsafe_b64decode(val + '==')