diff --git a/services/apm/apm.service.js b/services/apm/apm.service.js
index 3f4ccbea25..0725124e9c 100644
--- a/services/apm/apm.service.js
+++ b/services/apm/apm.service.js
@@ -5,11 +5,22 @@ const { BaseJsonService } = require('../base')
 const { InvalidResponse } = require('../errors')
 const { version: versionColor } = require('../../lib/color-formatters')
 const { metric, addv } = require('../../lib/text-formatters')
+const { nonNegativeInteger } = require('../validators.js')
+
+const apmSchema = Joi.object({
+  downloads: nonNegativeInteger,
+  releases: Joi.object({
+    latest: Joi.string().required(),
+  }),
+  metadata: Joi.object({
+    license: Joi.string().required(),
+  }),
+})
 
 class BaseAPMService extends BaseJsonService {
   async fetch(repo) {
     return this._requestJson({
-      schema: Joi.object(),
+      schema: apmSchema,
       url: `https://atom.io/api/packages/${repo}`,
       notFoundMessage: 'package not found',
     })
@@ -18,6 +29,15 @@ class BaseAPMService extends BaseJsonService {
   static get defaultBadgeData() {
     return { label: 'apm' }
   }
+
+  static get examples() {
+    return [
+      {
+        previewUrl: 'vim-mode',
+        keywords: ['atom'],
+      },
+    ]
+  }
 }
 
 class APMDownloads extends BaseAPMService {
@@ -43,15 +63,6 @@ class APMDownloads extends BaseAPMService {
       capture: ['repo'],
     }
   }
-
-  static get examples() {
-    return [
-      {
-        previewUrl: 'dm/vim-mode',
-        keywords: ['atom'],
-      },
-    ]
-  }
 }
 
 class APMVersion extends BaseAPMService {
@@ -77,15 +88,6 @@ class APMVersion extends BaseAPMService {
       capture: ['repo'],
     }
   }
-
-  static get examples() {
-    return [
-      {
-        previewUrl: 'v/vim-mode',
-        keywords: ['atom'],
-      },
-    ]
-  }
 }
 
 class APMLicense extends BaseAPMService {
@@ -115,15 +117,6 @@ class APMLicense extends BaseAPMService {
       capture: ['repo'],
     }
   }
-
-  static get examples() {
-    return [
-      {
-        previewUrl: 'l/vim-mode',
-        keywords: ['atom'],
-      },
-    ]
-  }
 }
 
 module.exports = {
diff --git a/services/appveyor/appveyor.service.js b/services/appveyor/appveyor.service.js
index 220cc3d2b2..ec4c9f4b98 100644
--- a/services/appveyor/appveyor.service.js
+++ b/services/appveyor/appveyor.service.js
@@ -3,6 +3,12 @@
 const Joi = require('joi')
 const { BaseJsonService } = require('../base')
 
+const appVeyorSchema = Joi.object({
+  build: Joi.object({
+    status: Joi.string().required(),
+  }),
+}).required()
+
 module.exports = class AppVeyor extends BaseJsonService {
   async handle({ repo, branch }) {
     let url = `https://ci.appveyor.com/api/projects/${repo}`
@@ -12,7 +18,7 @@ module.exports = class AppVeyor extends BaseJsonService {
     const {
       build: { status },
     } = await this._requestJson({
-      schema: Joi.object(),
+      schema: appVeyorSchema,
       url,
       notFoundMessage: 'project not found or access denied',
     })
diff --git a/services/cdnjs/cdnjs.service.js b/services/cdnjs/cdnjs.service.js
index 52861c8275..6b9cf7596f 100644
--- a/services/cdnjs/cdnjs.service.js
+++ b/services/cdnjs/cdnjs.service.js
@@ -6,12 +6,17 @@ const { NotFound } = require('../errors')
 const { addv: versionText } = require('../../lib/text-formatters')
 const { version: versionColor } = require('../../lib/color-formatters')
 
+const cdnjsSchema = Joi.object({
+  // optional due to non-standard 'not found' condition
+  version: Joi.string(),
+}).required()
+
 module.exports = class Cdnjs extends BaseJsonService {
   async handle({ library }) {
     const url = `https://api.cdnjs.com/libraries/${library}?fields=version`
     const json = await this._requestJson({
       url,
-      schema: Joi.any(),
+      schema: cdnjsSchema,
     })
 
     if (Object.keys(json).length === 0) {
@@ -19,11 +24,10 @@ module.exports = class Cdnjs extends BaseJsonService {
          status code = 200, body = {} */
       throw new NotFound()
     }
-    const version = json.version || 0
 
     return {
-      message: versionText(version),
-      color: versionColor(version),
+      message: versionText(json.version),
+      color: versionColor(json.version),
     }
   }
 
diff --git a/services/clojars/clojars.service.js b/services/clojars/clojars.service.js
index a02509b727..43f3f36ebb 100644
--- a/services/clojars/clojars.service.js
+++ b/services/clojars/clojars.service.js
@@ -5,12 +5,17 @@ const { BaseJsonService } = require('../base')
 const { NotFound } = require('../errors')
 const { version: versionColor } = require('../../lib/color-formatters')
 
+const clojarsSchema = Joi.object({
+  // optional due to non-standard 'not found' condition
+  version: Joi.string(),
+}).required()
+
 module.exports = class Clojars extends BaseJsonService {
   async handle({ clojar }) {
     const url = `https://clojars.org/${clojar}/latest-version.json`
     const json = await this._requestJson({
       url,
-      schema: Joi.any(),
+      schema: clojarsSchema,
     })
 
     if (Object.keys(json).length === 0) {
diff --git a/services/gem/gem-downloads.service.js b/services/gem/gem-downloads.service.js
new file mode 100644
index 0000000000..6d0fa3bf15
--- /dev/null
+++ b/services/gem/gem-downloads.service.js
@@ -0,0 +1,149 @@
+'use strict'
+
+const semver = require('semver')
+const Joi = require('joi')
+
+const { BaseJsonService } = require('../base')
+const { InvalidResponse } = require('../errors')
+const {
+  downloadCount: downloadCountColor,
+} = require('../../lib/color-formatters')
+const { metric } = require('../../lib/text-formatters')
+const { latest: latestVersion } = require('../../lib/version')
+const { nonNegativeInteger } = require('../validators.js')
+
+const gemsSchema = Joi.object({
+  downloads: nonNegativeInteger,
+  version_downloads: nonNegativeInteger,
+}).required()
+
+const versionsSchema = Joi.array()
+  .items(
+    Joi.object({
+      prerelease: Joi.boolean().required(),
+      number: Joi.string().required(),
+      downloads_count: nonNegativeInteger,
+    })
+  )
+  .min(1)
+  .required()
+
+module.exports = class GemDownloads extends BaseJsonService {
+  async fetch(repo, info) {
+    const endpoint = info === 'dv' ? 'versions/' : 'gems/'
+    const schema = info === 'dv' ? versionsSchema : gemsSchema
+    const url = `https://rubygems.org/api/v1/${endpoint}${repo}.json`
+    return this._requestJson({
+      url,
+      schema,
+    })
+  }
+
+  _getLabel(version, info) {
+    if (version) {
+      return 'downloads@' + version
+    } else {
+      if (info === 'dtv') {
+        return 'downloads@latest'
+      } else {
+        return 'downloads'
+      }
+    }
+  }
+
+  async handle({ info, rubygem }) {
+    const splitRubygem = rubygem.split('/')
+    const repo = splitRubygem[0]
+    let version =
+      splitRubygem.length > 1 ? splitRubygem[splitRubygem.length - 1] : null
+    version = version === 'stable' ? version : semver.valid(version)
+    const label = this._getLabel(version, info)
+    const json = await this.fetch(repo, info)
+
+    let downloads
+    if (info === 'dt') {
+      downloads = metric(json.downloads)
+    } else if (info === 'dtv') {
+      downloads = metric(json.version_downloads)
+    } else if (info === 'dv') {
+      let versionData
+      if (version !== null && version === 'stable') {
+        const versions = json
+          .filter(function(ver) {
+            return ver.prerelease === false
+          })
+          .map(function(ver) {
+            return ver.number
+          })
+        // Found latest stable version.
+        const stableVersion = latestVersion(versions)
+        versionData = json.filter(function(ver) {
+          return ver.number === stableVersion
+        })[0]
+        downloads = metric(versionData.downloads_count)
+      } else if (version !== null) {
+        versionData = json.filter(function(ver) {
+          return ver.number === version
+        })[0]
+
+        downloads = metric(versionData.downloads_count)
+      } else {
+        throw new InvalidResponse({
+          underlyingError: new Error('version is null'),
+        })
+      }
+    } else {
+      throw new InvalidResponse({
+        underlyingError: new Error('info is invalid'),
+      })
+    }
+
+    return {
+      label: label,
+      message: downloads,
+      color: downloadCountColor(downloads),
+    }
+  }
+
+  // Metadata
+  static get defaultBadgeData() {
+    return { label: 'downloads' }
+  }
+
+  static get category() {
+    return 'downloads'
+  }
+
+  static get url() {
+    return {
+      base: 'gem',
+      format: '(dt|dtv|dv)/(.+)',
+      capture: ['info', 'rubygem'],
+    }
+  }
+
+  static get examples() {
+    return [
+      {
+        title: 'Gem',
+        previewUrl: 'dv/rails/stable',
+        keywords: ['ruby'],
+      },
+      {
+        title: 'Gem',
+        previewUrl: 'dv/rails/4.1.0',
+        keywords: ['ruby'],
+      },
+      {
+        title: 'Gem',
+        previewUrl: 'dtv/rails',
+        keywords: ['ruby'],
+      },
+      {
+        title: 'Gem',
+        previewUrl: 'dt/rails',
+        keywords: ['ruby'],
+      },
+    ]
+  }
+}
diff --git a/services/gem/gem-owner.service.js b/services/gem/gem-owner.service.js
new file mode 100644
index 0000000000..2ac085499f
--- /dev/null
+++ b/services/gem/gem-owner.service.js
@@ -0,0 +1,51 @@
+'use strict'
+
+const Joi = require('joi')
+
+const { BaseJsonService } = require('../base')
+const { floorCount: floorCountColor } = require('../../lib/color-formatters')
+
+const ownerSchema = Joi.array().required()
+
+module.exports = class GemOwner extends BaseJsonService {
+  async handle({ user }) {
+    const url = `https://rubygems.org/api/v1/owners/${user}/gems.json`
+    const json = await this._requestJson({
+      url,
+      schema: ownerSchema,
+    })
+    const count = json.length
+
+    return {
+      message: count,
+      color: floorCountColor(count, 10, 50, 100),
+    }
+  }
+
+  // Metadata
+  static get defaultBadgeData() {
+    return { label: 'gems' }
+  }
+
+  static get category() {
+    return 'other'
+  }
+
+  static get url() {
+    return {
+      base: 'gem/u',
+      format: '(.+)',
+      capture: ['user'],
+    }
+  }
+
+  static get examples() {
+    return [
+      {
+        title: 'Gems',
+        previewUrl: 'raphink',
+        keywords: ['ruby'],
+      },
+    ]
+  }
+}
diff --git a/services/gem/gem-rank.service.js b/services/gem/gem-rank.service.js
new file mode 100644
index 0000000000..8e50f1b570
--- /dev/null
+++ b/services/gem/gem-rank.service.js
@@ -0,0 +1,95 @@
+'use strict'
+
+const Joi = require('joi')
+
+const { BaseJsonService } = require('../base')
+const { floorCount: floorCountColor } = require('../../lib/color-formatters')
+const { ordinalNumber } = require('../../lib/text-formatters')
+const { nonNegativeInteger } = require('../validators.js')
+
+const totalSchema = Joi.array()
+  .items(
+    Joi.object({
+      total_ranking: nonNegativeInteger,
+    })
+  )
+  .min(1)
+  .required()
+const dailySchema = Joi.array()
+  .items(
+    Joi.object({
+      daily_ranking: nonNegativeInteger,
+    })
+  )
+  .min(1)
+  .required()
+
+module.exports = class GemRank extends BaseJsonService {
+  _getApiUrl(repo, totalRank, dailyRank) {
+    let endpoint
+    if (totalRank) {
+      endpoint = '/total_ranking.json'
+    } else if (dailyRank) {
+      endpoint = '/daily_ranking.json'
+    }
+    return `http://bestgems.org/api/v1/gems/${repo}${endpoint}`
+  }
+
+  async handle({ info, repo }) {
+    const totalRank = info === 'rt'
+    const dailyRank = info === 'rd'
+    const schema = totalRank ? totalSchema : dailySchema
+    const url = this._getApiUrl(repo, totalRank, dailyRank)
+    const json = await this._requestJson({
+      url,
+      schema,
+    })
+
+    let rank
+    if (totalRank) {
+      rank = json[0].total_ranking
+    } else if (dailyRank) {
+      rank = json[0].daily_ranking
+    }
+    const count = Math.floor(100000 / rank)
+    let message = ordinalNumber(rank)
+    message += totalRank ? '' : ' daily'
+
+    return {
+      message: message,
+      color: floorCountColor(count, 10, 50, 100),
+    }
+  }
+
+  // Metadata
+  static get defaultBadgeData() {
+    return { label: 'rank' }
+  }
+
+  static get category() {
+    return 'rating'
+  }
+
+  static get url() {
+    return {
+      base: 'gem',
+      format: '(rt|rd)/(.+)',
+      capture: ['info', 'repo'],
+    }
+  }
+
+  static get examples() {
+    return [
+      {
+        title: 'Gems',
+        previewUrl: 'rt/puppet',
+        keywords: ['ruby'],
+      },
+      {
+        title: 'Gems',
+        previewUrl: 'rd/facter',
+        keywords: ['ruby'],
+      },
+    ]
+  }
+}
diff --git a/services/gem/gem-version.service.js b/services/gem/gem-version.service.js
new file mode 100644
index 0000000000..615f0d3cca
--- /dev/null
+++ b/services/gem/gem-version.service.js
@@ -0,0 +1,55 @@
+'use strict'
+
+const Joi = require('joi')
+
+const { BaseJsonService } = require('../base')
+const { addv: versionText } = require('../../lib/text-formatters')
+const { version: versionColor } = require('../../lib/color-formatters')
+
+// Response should contain a string key 'version'
+// In most cases this will be a SemVer
+// but the registry doesn't actually enforce this
+const versionSchema = Joi.object({
+  version: Joi.string().required(),
+}).required()
+
+module.exports = class GemVersion extends BaseJsonService {
+  async handle({ repo }) {
+    const url = `https://rubygems.org/api/v1/gems/${repo}.json`
+    const { version } = await this._requestJson({
+      url,
+      schema: versionSchema,
+    })
+    return {
+      message: versionText(version),
+      color: versionColor(version),
+    }
+  }
+
+  // Metadata
+  static get defaultBadgeData() {
+    return { label: 'gem' }
+  }
+
+  static get category() {
+    return 'version'
+  }
+
+  static get url() {
+    return {
+      base: 'gem/v',
+      format: '(.+)',
+      capture: ['repo'],
+    }
+  }
+
+  static get examples() {
+    return [
+      {
+        title: 'Gem',
+        previewUrl: 'formatador',
+        keywords: ['ruby'],
+      },
+    ]
+  }
+}
diff --git a/services/gem/gem.service.js b/services/gem/gem.service.js
deleted file mode 100644
index 03a9033b68..0000000000
--- a/services/gem/gem.service.js
+++ /dev/null
@@ -1,294 +0,0 @@
-'use strict'
-
-const semver = require('semver')
-const Joi = require('joi')
-
-const { BaseJsonService } = require('../base')
-const { InvalidResponse } = require('../errors')
-const { addv: versionText } = require('../../lib/text-formatters')
-const { version: versionColor } = require('../../lib/color-formatters')
-const {
-  floorCount: floorCountColor,
-  downloadCount: downloadCountColor,
-} = require('../../lib/color-formatters')
-const { metric, ordinalNumber } = require('../../lib/text-formatters')
-const { latest: latestVersion } = require('../../lib/version')
-
-class GemVersion extends BaseJsonService {
-  async handle({ repo }) {
-    const url = `https://rubygems.org/api/v1/gems/${repo}.json`
-    const { version } = await this._requestJson({
-      url,
-      schema: Joi.object(),
-    })
-    return {
-      message: versionText(version),
-      color: versionColor(version),
-    }
-  }
-
-  // Metadata
-  static get defaultBadgeData() {
-    return { label: 'gem' }
-  }
-
-  static get category() {
-    return 'version'
-  }
-
-  static get url() {
-    return {
-      base: 'gem/v',
-      format: '(.+)',
-      capture: ['repo'],
-    }
-  }
-
-  static get examples() {
-    return [
-      {
-        title: 'Gem',
-        previewUrl: 'formatador',
-        keywords: ['ruby'],
-      },
-    ]
-  }
-}
-
-class GemDownloads extends BaseJsonService {
-  fetch(repo, info) {
-    const endpoint = info === 'dv' ? 'versions/' : 'gems/'
-    const url = `https://rubygems.org/api/v1/${endpoint}${repo}.json`
-    return this._requestJson({
-      url,
-      schema: Joi.any(),
-    })
-  }
-
-  _getLabel(version, info) {
-    if (version) {
-      return 'downloads@' + version
-    } else {
-      if (info === 'dtv') {
-        return 'downloads@latest'
-      } else {
-        return 'downloads'
-      }
-    }
-  }
-
-  async handle({ info, rubygem }) {
-    const splitRubygem = rubygem.split('/')
-    const repo = splitRubygem[0]
-    let version =
-      splitRubygem.length > 1 ? splitRubygem[splitRubygem.length - 1] : null
-    version = version === 'stable' ? version : semver.valid(version)
-    const label = this._getLabel(version, info)
-    const json = await this.fetch(repo, info)
-
-    let downloads
-    if (info === 'dt') {
-      downloads = metric(json.downloads)
-    } else if (info === 'dtv') {
-      downloads = metric(json.version_downloads)
-    } else if (info === 'dv') {
-      let versionData
-      if (version !== null && version === 'stable') {
-        const versions = json
-          .filter(function(ver) {
-            return ver.prerelease === false
-          })
-          .map(function(ver) {
-            return ver.number
-          })
-        // Found latest stable version.
-        const stableVersion = latestVersion(versions)
-        versionData = json.filter(function(ver) {
-          return ver.number === stableVersion
-        })[0]
-        downloads = metric(versionData.downloads_count)
-      } else if (version !== null) {
-        versionData = json.filter(function(ver) {
-          return ver.number === version
-        })[0]
-
-        downloads = metric(versionData.downloads_count)
-      } else {
-        throw new InvalidResponse({
-          underlyingError: new Error('version is null'),
-        })
-      }
-    } else {
-      throw new InvalidResponse({
-        underlyingError: new Error('info is invalid'),
-      })
-    }
-
-    return {
-      label: label,
-      message: downloads,
-      color: downloadCountColor(downloads),
-    }
-  }
-
-  // Metadata
-  static get defaultBadgeData() {
-    return { label: 'downloads' }
-  }
-
-  static get category() {
-    return 'downloads'
-  }
-
-  static get url() {
-    return {
-      base: 'gem',
-      format: '(dt|dtv|dv)/(.+)',
-      capture: ['info', 'rubygem'],
-    }
-  }
-
-  static get examples() {
-    return [
-      {
-        title: 'Gem',
-        previewUrl: 'dv/rails/stable',
-        keywords: ['ruby'],
-      },
-      {
-        title: 'Gem',
-        previewUrl: 'dv/rails/4.1.0',
-        keywords: ['ruby'],
-      },
-      {
-        title: 'Gem',
-        previewUrl: 'dtv/rails',
-        keywords: ['ruby'],
-      },
-      {
-        title: 'Gem',
-        previewUrl: 'dt/rails',
-        keywords: ['ruby'],
-      },
-    ]
-  }
-}
-
-class GemOwner extends BaseJsonService {
-  async handle({ user }) {
-    const url = `https://rubygems.org/api/v1/owners/${user}/gems.json`
-    const json = await this._requestJson({
-      url,
-      schema: Joi.array(),
-    })
-    const count = json.length
-
-    return {
-      message: count,
-      color: floorCountColor(count, 10, 50, 100),
-    }
-  }
-
-  // Metadata
-  static get defaultBadgeData() {
-    return { label: 'gems' }
-  }
-
-  static get category() {
-    return 'other'
-  }
-
-  static get url() {
-    return {
-      base: 'gem/u',
-      format: '(.+)',
-      capture: ['user'],
-    }
-  }
-
-  static get examples() {
-    return [
-      {
-        title: 'Gems',
-        previewUrl: 'raphink',
-        keywords: ['ruby'],
-      },
-    ]
-  }
-}
-
-class GemRank extends BaseJsonService {
-  _getApiUrl(repo, totalRank, dailyRank) {
-    let endpoint
-    if (totalRank) {
-      endpoint = '/total_ranking.json'
-    } else if (dailyRank) {
-      endpoint = '/daily_ranking.json'
-    }
-    return `http://bestgems.org/api/v1/gems/${repo}${endpoint}`
-  }
-
-  async handle({ info, repo }) {
-    const totalRank = info === 'rt'
-    const dailyRank = info === 'rd'
-    const url = this._getApiUrl(repo, totalRank, dailyRank)
-    const json = await this._requestJson({
-      url,
-      schema: Joi.array(),
-    })
-
-    let rank
-    if (totalRank) {
-      rank = json[0].total_ranking
-    } else if (dailyRank) {
-      rank = json[0].daily_ranking
-    }
-    const count = Math.floor(100000 / rank)
-    let message = ordinalNumber(rank)
-    message += totalRank ? '' : ' daily'
-
-    return {
-      message: message,
-      color: floorCountColor(count, 10, 50, 100),
-    }
-  }
-
-  // Metadata
-  static get defaultBadgeData() {
-    return { label: 'rank' }
-  }
-
-  static get category() {
-    return 'rating'
-  }
-
-  static get url() {
-    return {
-      base: 'gem',
-      format: '(rt|rd)/(.+)',
-      capture: ['info', 'repo'],
-    }
-  }
-
-  static get examples() {
-    return [
-      {
-        title: 'Gems',
-        previewUrl: 'rt/puppet',
-        keywords: ['ruby'],
-      },
-      {
-        title: 'Gems',
-        previewUrl: 'rd/facter',
-        keywords: ['ruby'],
-      },
-    ]
-  }
-}
-
-module.exports = {
-  GemVersion,
-  GemDownloads,
-  GemOwner,
-  GemRank,
-}
diff --git a/services/npm/npm-downloads.service.js b/services/npm/npm-downloads.service.js
index a8e0be3576..aae45cbcbc 100644
--- a/services/npm/npm-downloads.service.js
+++ b/services/npm/npm-downloads.service.js
@@ -3,13 +3,11 @@
 const Joi = require('joi')
 const { BaseJsonService } = require('../base')
 const { metric } = require('../../lib/text-formatters')
+const { nonNegativeInteger } = require('../validators.js')
 
 // https://github.com/npm/registry/blob/master/docs/download-counts.md#output
 const pointResponseSchema = Joi.object({
-  downloads: Joi.number()
-    .integer()
-    .min(0)
-    .required(),
+  downloads: nonNegativeInteger,
 }).required()
 
 // https://github.com/npm/registry/blob/master/docs/download-counts.md#output-1
diff --git a/services/validators.js b/services/validators.js
new file mode 100644
index 0000000000..50723b609e
--- /dev/null
+++ b/services/validators.js
@@ -0,0 +1,12 @@
+'use strict'
+
+const Joi = require('joi')
+
+const nonNegativeInteger = Joi.number()
+  .integer()
+  .min(0)
+  .required()
+
+module.exports = {
+  nonNegativeInteger,
+}