diff --git a/ChangeLog b/ChangeLog
index c8453e5..5ad5c04 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -8,6 +8,8 @@ ChangeLog
 
     * Add support for Django 3.1
     * Add support for Python 3.7 / 3.8 / 3.9
+    * `#115 <https://github.com/rbarrois/python-semanticversion/issues/98>`_:
+      Improve ``NpmSpec`` compatibility with official ``node-semver`` implementation by allowing some whitespace before the version (e.g. ``>  1.2.3``, ``1.2.3    - 4.5.6``) and adding ``~>`` as an alias for ``~``.
 
 
 2.8.5 (2020-04-29)
@@ -15,7 +17,7 @@ ChangeLog
 
 *Bugfix:*
 
-    * `98 <https://github.com/rbarrois/python-semanticversion/issues/98>`_:
+    * `#98 <https://github.com/rbarrois/python-semanticversion/issues/98>`_:
       Properly handle wildcards in ``SimpleSpec`` (e.g. ``==1.2.*``).
 
 
diff --git a/semantic_version/base.py b/semantic_version/base.py
index 871ccb0..3692576 100644
--- a/semantic_version/base.py
+++ b/semantic_version/base.py
@@ -1230,15 +1230,21 @@ class Parser:
 
         NUMBER = r'x|X|\*|0|[1-9][0-9]*'
         PART = r'[a-zA-Z0-9.-]*'
+        OP = r'~>|<=|>=|>|<|\^|~|='
         NPM_SPEC_BLOCK = re.compile(r"""
             ^(?:v)?                     # Strip optional initial v
-            (?P<op><|<=|>=|>|=|\^|~|)   # Operator, can be empty
+            (?P<op>{op}|)               # Operator, can be empty
             (?P<major>{nb})(?:\.(?P<minor>{nb})(?:\.(?P<patch>{nb}))?)?
             (?:-(?P<prerel>{part}))?    # Optional re-release
             (?:\+(?P<build>{part}))?    # Optional build
-            $""".format(nb=NUMBER, part=PART),
+            $""".format(nb=NUMBER, part=PART, op=OP),
             re.VERBOSE,
         )
+        OP_RE = re.compile(r"""
+            ^(?:{op})$      # A standalone operator, cannot be empty
+            """.format(op=OP),
+           re.VERBOSE,
+        )
 
         @classmethod
         def range(cls, operator, target):
@@ -1256,15 +1262,21 @@ def parse(cls, expression):
                 subclauses = []
                 if cls.HYPHEN in group:
                     low, high = group.split(cls.HYPHEN, 2)
-                    subclauses = cls.parse_simple('>=' + low) + cls.parse_simple('<=' + high)
+                    subclauses = cls.parse_simple('>=' + low.strip()) + cls.parse_simple('<=' + high.strip())
 
                 else:
-                    blocks = group.split(' ')
+                    blocks = group.split()
+                    maybe_prepend_op = None
                     for block in blocks:
-                        if not cls.NPM_SPEC_BLOCK.match(block):
+                        block = maybe_prepend_op + block if maybe_prepend_op else block
+                        if cls.NPM_SPEC_BLOCK.match(block):
+                            subclauses.extend(cls.parse_simple(block))
+                            maybe_prepend_op = None
+                        elif maybe_prepend_op is None and cls.OP_RE.match(block):
+                            maybe_prepend_op = block
+                        else:
                             raise ValueError("Invalid NPM block in %r: %r" % (expression, block))
 
-                        subclauses.extend(cls.parse_simple(block))
 
                 prerelease_clauses = []
                 non_prerel_clauses = []
@@ -1314,6 +1326,7 @@ def parse(cls, expression):
 
         PREFIX_ALIASES = {
             '': PREFIX_EQ,
+            '~>': PREFIX_TILDE,
         }
 
         PREFIX_TO_OPERATOR = {
diff --git a/tests/test_npm.py b/tests/test_npm.py
index 2102cd8..8dc8fff 100644
--- a/tests/test_npm.py
+++ b/tests/test_npm.py
@@ -66,21 +66,35 @@ def test_spec(self):
                     self.assertNotIn(base.Version(version), base.NpmSpec(spec))
 
     expansions = {
+        # Basic
+        '>1.2.3': '>1.2.3',
+        '<1.2.3': '<1.2.3',
+        '<=1.2.3': '<=1.2.3',
+
         # Hyphen ranges
         '1.2.3 - 2.3.4': '>=1.2.3 <=2.3.4',
         '1.2 - 2.3.4': '>=1.2.0 <=2.3.4',
         '1.2.3 - 2.3': '>=1.2.3 <2.4.0',
         '1.2.3 - 2': '>=1.2.3 <3',
+        '1.2.3    - 2': '>=1.2.3 <3',
 
         # X-Ranges
         '*': '>=0.0.0',
+        '>=*': '>=0.0.0',
         '1.x': '>=1.0.0 <2.0.0',
         '1.2.x': '>=1.2.0 <1.3.0',
         '': '*',
+        'x': '*',
         '1': '1.x.x',
         '1.x.x': '>=1.0.0 <2.0.0',
         '1.2': '1.2.x',
 
+        # Partial GT LT Ranges
+        '>=1': '>=1.0.0',
+        '>1': '>=2.0.0',
+        '>1.2': '>=1.3.0',
+        '<1': '<1.0.0',
+
         # Tilde ranges
         '~1.2.3': '>=1.2.3 <1.3.0',
         '~1.2': '>=1.2.0 <1.3.0',
@@ -89,6 +103,10 @@ def test_spec(self):
         '~0.2': '>=0.2.0 <0.3.0',
         '~0': '>=0.0.0 <1.0.0',
         '~1.2.3-beta.2': '>=1.2.3-beta.2 <1.3.0',
+        '~ 1.2.3': '>=1.2.3 <1.3.0',
+        '~    1.2.3': '>=1.2.3 <1.3.0',
+        '~>1.2.3': '>=1.2.3 <1.3.0',
+        '~> 1.2.3': '>=1.2.3 <1.3.0',
 
         # Caret ranges
         '^1.2.3': '>=1.2.3 <2.0.0',
@@ -101,6 +119,23 @@ def test_spec(self):
         '^0.0': '>=0.0.0 <0.1.0',
         '^1.x': '>=1.0.0 <2.0.0',
         '^0.x': '>=0.0.0 <1.0.0',
+        '^0': '>=0.0.0 <1.0.0',
+        '^ 1.2.3': '>=1.2.3 <2.0.0',
+        '^   1.2.3': '>=1.2.3 <2.0.0',
+
+        # Weird whitespace ranges
+        '>= 1.2.3': '>=1.2.3',
+        '>=\t1.2.3': '>=1.2.3',
+        '>=   1.2.3': '>=1.2.3',
+        '>=1.2.3      <2.0.0': '>=1.2.3 <2.0.0',
+        '   >=1.2.3 <2.0.0    ': '>=1.2.3 <2.0.0',
+        '>= 1.2.3 <  2.0.0': '>=1.2.3 <2.0.0',
+        '>=1.2.3 < 2.0.0': '>=1.2.3 <2.0.0',
+        '>= 1.2.3 < 2.0.0': '>=1.2.3 <2.0.0',
+        '>=  1.2.3 <    2.0.0': '>=1.2.3 <2.0.0',
+        '   >=1.2.3 <2.0.0    ': '>=1.2.3 <2.0.0',
+        '1.2.7 ||    >=1.2.9 <2.0.0': '1.2.7 || >=1.2.9 <2.0.0',
+        '1.2.7 ||    >= 1.2.9 < 2.0.0': '1.2.7 || >=1.2.9 <2.0.0',
     }
 
     def test_expand(self):
@@ -110,3 +145,38 @@ def test_expand(self):
                     base.NpmSpec(source).clause,
                     base.NpmSpec(expanded).clause,
                 )
+
+    equivalent_npmspecs = {
+        '||': '*',
+        #'>1.2.3 || *': '*',
+        #'>=1.2.1 <=2.3.4': '>1.2.0 <2.3.5',
+    }
+
+    def test_equivalent(self):
+        # like expand, but we also simplify both sides
+        # NOTE: some specs can be equivalent but don't
+        # currently simplify to the same clauses
+        for left, right in self.equivalent_npmspecs.items():
+            with self.subTest(l=left, r=right):
+                self.assertEqual(
+                    base.NpmSpec(left).clause.simplify(),
+                    base.NpmSpec(right).clause.simplify(),
+                )
+
+    invalid_npmspecs = [
+        '==0.1.2',
+        '>>0.1.2',
+        '> = 0.1.2',
+        '<=>0.1.2',
+        '~1.2.3beta',
+        '~=1.2.3',
+        '>01.02.03',
+        '!0.1.2',
+        '!=0.1.2',
+    ]
+
+    def test_invalid(self):
+        for invalid in self.invalid_npmspecs:
+            with self.subTest(spec=invalid):
+                with self.assertRaises(ValueError, msg="NpmSpec(%r) should be invalid" % invalid):
+                    base.NpmSpec(invalid)