diff --git a/lib/version.js b/lib/version.js
index be4b7a7c78241..1c83e068e13ae 100644
--- a/lib/version.js
+++ b/lib/version.js
@@ -11,18 +11,34 @@ const semver = require('semver');
 
 // Given a list of versions (as strings), return the latest version.
 // Return undefined if no version could be found.
-function latest(versions) {
+function latest(versions, { pre = false } = {}) {
   let version = '';
   let origVersions = versions;
-  versions = versions.filter(function(version) {
-    return (/[0-9]/).test(version);
+  // return all results that are likely semver compatible versions
+  versions = origVersions.filter(function(version) {
+    return (/\d+\.\d+/).test(version);
   });
+  // If no semver versions then look for single numbered versions
+  if (!versions.length){
+    versions = origVersions.filter(function(version) {
+      return (/\d+/).test(version);
+    });
+  }
+  if (!pre){
+    // remove pre-releases from array
+    versions = versions.filter(function(version) {
+      return !(/\d+-\w+/).test(version);
+    });
+  }
   try {
-    version = semver.maxSatisfying(versions, '');
+    version = versions.sort((a, b) => {
+      // coerce to string then lowercase otherwise alpha > RC
+      return semver.rcompare((''+a).toLowerCase(), (''+b).toLowerCase(), /* loose */ true);
+    })[0];
   } catch(e) {
     version = latestDottedVersion(versions);
   }
-  if (version === undefined) {
+  if (version === undefined || version === null) {
     origVersions = origVersions.sort();
     version = origVersions[origVersions.length - 1];
   }
@@ -83,14 +99,14 @@ function compareDottedVersion(v1, v2) {
 // Slice the specified number of dotted parts from the given semver version.
 // e.g. slice('2.4.7', 'minor') -> '2.4'
 function slice(v, releaseType) {
-  if (! semver.valid(v)) {
+  if (! semver.valid(v, /* loose */ true)) {
     return null;
   }
 
-  const major = semver.major(v);
-  const minor = semver.minor(v);
-  const patch = semver.patch(v);
-  const prerelease = semver.prerelease(v);
+  const major = semver.major(v, /* loose */ true);
+  const minor = semver.minor(v, /* loose */ true);
+  const patch = semver.patch(v, /* loose */ true);
+  const prerelease = semver.prerelease(v, /* loose */ true);
 
   const dottedParts = {
     major: [major],
@@ -115,7 +131,7 @@ function minor(v) {
 }
 
 function rangeStart(v) {
-  const range = new semver.Range(v);
+  const range = new semver.Range(v, /* loose */ true);
   return range.set[0][0].semver.version;
 }
 
diff --git a/lib/version.spec.js b/lib/version.spec.js
index f51e28a94693c..831a9852ab453 100644
--- a/lib/version.spec.js
+++ b/lib/version.spec.js
@@ -2,6 +2,7 @@
 
 const { test, given } = require('sazerac');
 const { latest, slice, rangeStart } = require('./version');
+const includePre = true;
 
 describe('Version helpers', function () {
   test(latest, () => {
@@ -10,32 +11,51 @@ describe('Version helpers', function () {
     given(['1.0.0', '2.0.0', '3.0.0']).expect('3.0.0');
     given(['0.0.1', '0.0.10', '0.0.2', '0.0.20']).expect('0.0.20');
 
-    // Simple dotted versions.
-    given(['1.0.0', 'v1.0.2', 'r1.0.1', 'release-2.0.0']).expect('release-2.0.0');
-    given(['1.0.0', 'v2.0.0', 'r1.0.1', 'release-1.0.3']).expect('v2.0.0');
-    given(['2.0.0', 'v1.0.3', 'r1.0.1', 'release-1.0.3']).expect('2.0.0');
-    given(['1.0.0', 'v1.0.2', 'r2.0.0', 'release-1.0.3']).expect('r2.0.0');
+    // "not-quite-valid" semver versions
+    given(['1.0.00', '1.0.02', '1.0.01']).expect('1.0.02');
+    given(['1.0.05', '2.0.05', '3.0.05']).expect('3.0.05');
+    given(['0.0.01', '0.0.010', '0.0.02', '0.0.020']).expect('0.0.020');
+
+    // Mixed style versions. - include pre-releases
+    given(['1.0.0', 'v1.0.2', 'r1.0.1', 'release-2.0.0', 'v1.0.1-alpha.1'], { pre: includePre }).expect('release-2.0.0');
+    given(['1.0.0', 'v2.0.0', 'r1.0.1', 'release-1.0.3', 'v1.0.1-alpha.1'], { pre: includePre }).expect('v2.0.0');
+    given(['2.0.0', 'v1.0.3', 'r1.0.1', 'release-1.0.3', 'v1.0.1-alpha.1'], { pre: includePre }).expect('2.0.0');
+    given(['1.0.0', 'v1.0.2', 'r2.0.0', 'release-1.0.3', 'v1.0.1-alpha.1'], { pre: includePre }).expect('r2.0.0');
+    given(['1.0.0', 'v1.0.2', 'r2.0.0', 'release-1.0.3', 'v2.0.1-alpha.1'], { pre: includePre }).expect('v2.0.1-alpha.1');
 
     // Versions with 'v' prefix.
+    given(['v1.0.0', 'v1.0.2', 'v1.0.1']).expect('v1.0.2');
+    given(['v1.0.0', 'v3.0.0', 'v2.0.0']).expect('v3.0.0');
+
+    // Simple (2 number) versions.
     given(['0.1', '0.3', '0.2']).expect('0.3');
     given(['0.1', '0.5', '0.12', '0.21']).expect('0.21');
     given(['1.0', '2.0', '3.0']).expect('3.0');
 
-    // Versions with '-release' prefix
-    given(['v1.0.0', 'v1.0.2', 'v1.0.1']).expect('v1.0.2');
-    given(['v1.0.0', 'v3.0.0', 'v2.0.0']).expect('v3.0.0');
+    // Simple (one-number) versions
+    given(['2', '10', '1']).expect('10');
+
+    // Include pre-releases
+    given(['v1.0.1-alpha.2', 'v1.0.1-alpha.1', 'v1.0.1-beta.3', 'v1.0.1-beta.1', 'v1.0.1-RC.1', 'v1.0.1-RC.2', 'v1.0.0'], { pre: includePre }).expect('v1.0.1-RC.2');
+    given(['v1.0.1-alpha.2', 'v1.0.1-alpha.1', 'v1.0.1-beta.3', 'v1.0.1-beta.1', 'v1.0.1-RC.1', 'v1.0.1-RC.2','v1.0.1'], { pre: includePre }).expect('v1.0.1');
+    // Exclude pre-releases
+    given(['v1.0.1-alpha.2', 'v1.0.1-alpha.1', 'v1.0.1-beta.3', 'v1.0.1-beta.1', 'v1.0.1-RC.1', 'v1.0.1-RC.2', 'v1.0.0']).expect('v1.0.0');
+    given(['v1.0.1-alpha.2', 'v1.0.1-alpha.1', 'v1.0.1-beta.3', 'v1.0.1-beta.1', 'v1.0.1-RC.1', 'v1.0.1-RC.2','v1.0.1']).expect('v1.0.1');
 
-    // Versions with '-release' prefix
+    // Versions with 'release-' prefix
     given(['release-1.0.0', 'release-1.0.2', 'release-1.0.20', 'release-1.0.3']).expect('release-1.0.20');
 
-    // Simple (one-number) versions
-    given(['2', '10', '1']).expect('10');
+    // Semver mixed with non semver versions
+    given(['1.0.0', '1.0.2', '1.1', '1.0', 'notaversion2', '12bcde4']).expect('1.1');
   });
 
   test(slice, () => {
     given('2.4.7', 'major').expect('2');
     given('2.4.7', 'minor').expect('2.4');
     given('2.4.7', 'patch').expect('2.4.7');
+    given('02.4.7', 'major').expect('2');
+    given('2.04.7', 'minor').expect('2.4');
+    given('2.4.07', 'patch').expect('2.4.7');
     given('2.4.7-alpha.1', 'major').expect('2-alpha.1');
     given('2.4.7-alpha.1', 'minor').expect('2.4-alpha.1');
     given('2.4.7-alpha.1', 'patch').expect('2.4.7-alpha.1');
diff --git a/server.js b/server.js
index 7d45012c3658f..5d59e364129b9 100644
--- a/server.js
+++ b/server.js
@@ -2489,12 +2489,13 @@ cache(function(data, match, sendBadge, request) {
 }));
 
 // Dart's pub version integration.
-camp.route(/^\/pub\/v\/(.*)\.(svg|png|gif|jpg|json)$/,
+camp.route(/^\/pub\/v(pre)?\/(.*)\.(svg|png|gif|jpg|json)$/,
 cache(function(data, match, sendBadge, request) {
-  var userRepo = match[1]; // eg, "box2d"
-  var format = match[2];
-  var apiUrl = 'https://pub.dartlang.org/packages/' + userRepo + '.json';
-  var badgeData = getBadgeData('pub', data);
+  const includePre = Boolean(match[1]);
+  const userRepo = match[2]; // eg, "box2d"
+  const format = match[3];
+  const apiUrl = 'https://pub.dartlang.org/packages/' + userRepo + '.json';
+  let badgeData = getBadgeData('pub', data);
   request(apiUrl, function(err, res, buffer) {
     if (err != null) {
       badgeData.text[1] = 'inaccessible';
@@ -2505,7 +2506,7 @@ cache(function(data, match, sendBadge, request) {
       var data = JSON.parse(buffer);
       // Grab the latest stable version, or an unstable
       var versions = data.versions;
-      var version = latestVersion(versions);
+      var version = latestVersion(versions, { pre: includePre });
       badgeData.text[1] = versionText(version);
       badgeData.colorscheme = versionColor(version);
       sendBadge(format, badgeData);
@@ -3570,13 +3571,14 @@ cache(function (data, match, sendBadge, request) {
 }));
 
 // GitHub tag integration.
-camp.route(/^\/github\/tag\/([^/]+)\/([^/]+)\.(svg|png|gif|jpg|json)$/,
+camp.route(/^\/github\/tag(-?pre)?\/([^/]+)\/([^/]+)\.(svg|png|gif|jpg|json)$/,
 cache(function(data, match, sendBadge, request) {
-  var user = match[1];  // eg, expressjs/express
-  var repo = match[2];
-  var format = match[3];
-  var apiUrl = githubApiUrl + '/repos/' + user + '/' + repo + '/tags';
-  var badgeData = getBadgeData('tag', data);
+  const includePre = Boolean(match[1]);
+  const user = match[2];  // eg, expressjs/express
+  const repo = match[3];
+  const format = match[4];
+  const apiUrl = githubApiUrl + '/repos/' + user + '/' + repo + '/tags';
+  let badgeData = getBadgeData('tag', data);
   if (badgeData.template === 'social') {
     badgeData.logo = getLogo('github', data);
   }
@@ -3589,7 +3591,7 @@ cache(function(data, match, sendBadge, request) {
     try {
       var data = JSON.parse(buffer);
       var versions = data.map(function(e) { return e.name; });
-      var tag = latestVersion(versions);
+      var tag = latestVersion(versions, { pre: includePre });
       badgeData.text[1] = versionText(tag);
       badgeData.colorscheme = versionColor(tag);
       sendBadge(format, badgeData);