diff --git a/.gitignore b/.gitignore
index 82f3a88..55d6fb1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+ci-info.cabal
 dist
 dist-*
 cabal-dev
diff --git a/README.md b/README.md
index 50dcd44..521937e 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,19 @@
 # ci-info-hs
- Get details about the current Continuous Integration environment - Haskell port of https://github.com/watson/ci-info
+
+Checks if the current environment is a Continuous Integration server.
+
+This is a Haskell port of [watson/ci-info](https://github.com/watson/ci-info).
+
+## Usage
+
+Check if the current environment is a CI server:
+
+```haskell
+isCI :: IO Bool
+```
+
+Get the name of the CI vendor. Returns `Nothing` if no CI could be detected. Returns `Just CI_UNKNOWN_VENDOR` if a CI was detected, but the vendor name could not be determined:
+
+```haskell
+getCI :: IO (Maybe CI)
+```
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
index 0000000..ebdc00e
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,3 @@
+import           Distribution.Simple
+
+main = defaultMain
diff --git a/package.yaml b/package.yaml
new file mode 100644
index 0000000..7ec4e93
--- /dev/null
+++ b/package.yaml
@@ -0,0 +1,36 @@
+name:                ci-info
+version:             0.1.0.0
+github:              "hasura/ci-info-hs"
+license:             MIT
+author:              "Ajeet D'Souza"
+maintainer:          "build@hasura.io"
+copyright:           "2019 Hasura Inc."
+
+extra-source-files:
+- README.md
+
+description:         Please see the README on GitHub at <https://github.com/hasura/ci-info-hs#readme>
+
+dependencies:
+- base >= 4.7 && < 5
+- aeson
+- aeson-casing
+- hashable
+- template-haskell
+- th-lift-instances
+- text
+- unordered-containers
+
+ghc-options:
+- -Wall
+- -Wincomplete-uni-patterns
+- -Wincomplete-record-updates
+- -Wcompat
+- -Widentities
+- -Wredundant-constraints
+- -Wmissing-export-lists
+- -Wpartial-fields
+
+library:
+  exposed-modules: CI
+  source-dirs: src
diff --git a/res/vendors.json b/res/vendors.json
new file mode 100644
index 0000000..2e691b0
--- /dev/null
+++ b/res/vendors.json
@@ -0,0 +1,159 @@
+[
+  {
+    "name": "AppVeyor",
+    "constant": "APPVEYOR",
+    "env": "APPVEYOR",
+    "pr": "APPVEYOR_PULL_REQUEST_NUMBER"
+  },
+  {
+    "name": "Azure Pipelines",
+    "constant": "AZURE_PIPELINES",
+    "env": "SYSTEM_TEAMFOUNDATIONCOLLECTIONURI",
+    "pr": "SYSTEM_PULLREQUEST_PULLREQUESTID"
+  },
+  {
+    "name": "Bamboo",
+    "constant": "BAMBOO",
+    "env": "bamboo_planKey"
+  },
+  {
+    "name": "Bitbucket Pipelines",
+    "constant": "BITBUCKET",
+    "env": "BITBUCKET_COMMIT",
+    "pr": "BITBUCKET_PR_ID"
+  },
+  {
+    "name": "Bitrise",
+    "constant": "BITRISE",
+    "env": "BITRISE_IO",
+    "pr": "BITRISE_PULL_REQUEST"
+  },
+  {
+    "name": "Buddy",
+    "constant": "BUDDY",
+    "env": "BUDDY_WORKSPACE_ID",
+    "pr": "BUDDY_EXECUTION_PULL_REQUEST_ID"
+  },
+  {
+    "name": "Buildkite",
+    "constant": "BUILDKITE",
+    "env": "BUILDKITE",
+    "pr": { "env": "BUILDKITE_PULL_REQUEST", "ne": "false" }
+  },
+  {
+    "name": "CircleCI",
+    "constant": "CIRCLE",
+    "env": "CIRCLECI",
+    "pr": "CIRCLE_PULL_REQUEST"
+  },
+  {
+    "name": "Cirrus CI",
+    "constant": "CIRRUS",
+    "env": "CIRRUS_CI",
+    "pr": "CIRRUS_PR"
+  },
+  {
+    "name": "AWS CodeBuild",
+    "constant": "CODEBUILD",
+    "env": "CODEBUILD_BUILD_ARN"
+  },
+  {
+    "name": "Codeship",
+    "constant": "CODESHIP",
+    "env": { "CI_NAME": "codeship" }
+  },
+  {
+    "name": "Drone",
+    "constant": "DRONE",
+    "env": "DRONE",
+    "pr": { "DRONE_BUILD_EVENT": "pull_request" }
+  },
+  {
+    "name": "dsari",
+    "constant": "DSARI",
+    "env": "DSARI"
+  },
+  {
+    "name": "GitLab CI",
+    "constant": "GITLAB",
+    "env": "GITLAB_CI"
+  },
+  {
+    "name": "GoCD",
+    "constant": "GOCD",
+    "env": "GO_PIPELINE_LABEL"
+  },
+  {
+    "name": "Hudson",
+    "constant": "HUDSON",
+    "env": "HUDSON_URL"
+  },
+  {
+    "name": "Jenkins",
+    "constant": "JENKINS",
+    "env": ["JENKINS_URL", "BUILD_ID"],
+    "pr": { "any": ["ghprbPullId", "CHANGE_ID"] }
+  },
+  {
+    "name": "Magnum CI",
+    "constant": "MAGNUM",
+    "env": "MAGNUM"
+  },
+  {
+    "name": "Netlify CI",
+    "constant": "NETLIFY",
+    "env": "NETLIFY_BUILD_BASE",
+    "pr": { "env": "PULL_REQUEST", "ne": "false" }
+  },
+  {
+    "name": "Nevercode",
+    "constant": "NEVERCODE",
+    "env": "NEVERCODE",
+    "pr": { "env": "NEVERCODE_PULL_REQUEST", "ne": "false" }
+  },
+  {
+    "name": "Sail CI",
+    "constant": "SAIL",
+    "env": "SAILCI",
+    "pr": "SAIL_PULL_REQUEST_NUMBER"
+  },
+  {
+    "name": "Semaphore",
+    "constant": "SEMAPHORE",
+    "env": "SEMAPHORE",
+    "pr": "PULL_REQUEST_NUMBER"
+  },
+  {
+    "name": "Shippable",
+    "constant": "SHIPPABLE",
+    "env": "SHIPPABLE",
+    "pr": { "IS_PULL_REQUEST": "true" }
+  },
+  {
+    "name": "Solano CI",
+    "constant": "SOLANO",
+    "env": "TDDIUM",
+    "pr": "TDDIUM_PR_ID"
+  },
+  {
+    "name": "Strider CD",
+    "constant": "STRIDER",
+    "env": "STRIDER"
+  },
+  {
+    "name": "TaskCluster",
+    "constant": "TASKCLUSTER",
+    "env": ["TASK_ID", "RUN_ID"]
+  },
+  {
+    "name": "TeamCity",
+    "constant": "TEAMCITY",
+    "env": "TEAMCITY_VERSION"
+  },
+  {
+    "name": "Travis CI",
+    "constant": "TRAVIS",
+    "env": "TRAVIS",
+    "pr": { "env": "TRAVIS_PULL_REQUEST", "ne": "false" }
+  }
+]
diff --git a/src/CI.hs b/src/CI.hs
new file mode 100644
index 0000000..1d203a5
--- /dev/null
+++ b/src/CI.hs
@@ -0,0 +1,59 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+module CI
+  ( Types.CI(..)
+  , isCI
+  , getCI
+  ) where
+
+import           Control.Arrow       ((***))
+import           Data.Bool           (bool)
+import           Data.Foldable       (find)
+import           Data.Maybe          (isJust)
+import           System.Environment  (getEnvironment)
+
+import           CI.TH               (getVendors)
+
+import qualified Data.HashMap.Strict as HashMap
+import qualified Data.Text           as T
+
+import qualified CI.Types            as Types
+
+
+vendors :: [Types.Vendor]
+vendors = $(getVendors)
+
+getCI :: IO (Maybe Types.CI)
+getCI = do
+  env <- mkEnvMap <$> getEnvironment
+  let maybeVendor = find (checkVendor env) vendors
+  return
+    $ case maybeVendor of
+      Nothing     -> bool Nothing (Just Types.CI_UNKNOWN_VENDOR)
+        $ checkUnknownVendor env
+      Just vendor -> Just $ Types.vendorConstant vendor
+  where
+    checkVendor env vendor = case Types.vendorEnv vendor of
+      (Types.VendorEnvString text)    -> HashMap.member text env
+      (Types.VendorEnvList list)      -> all (`HashMap.member` env) list
+      (Types.VendorEnvObject hashMap) -> all
+        (\(k, v) -> HashMap.lookup k env == Just v)
+        $ HashMap.toList hashMap
+
+    -- check vendor neutral environment variables
+    checkUnknownVendor env = any (`HashMap.member` env) unknownVendorEnvVars
+
+    unknownVendorEnvVars = map
+      Types.EnvVarName
+      [ "CI" -- Travis CI, CircleCI, Cirrus CI, Gitlab CI, Appveyor, CodeShip, dsari
+      , "CONTINUOUS_INTEGRATION" -- Travis CI, Cirrus CI
+      , "BUILD_NUMBER" -- Jenkins, TeamCity
+      , "RUN_ID" -- TaskCluster, dsari
+      ]
+
+    mkEnvMap = HashMap.fromList
+      . map (Types.EnvVarName . T.pack *** Types.EnvVarValue . T.pack)
+
+isCI :: IO Bool
+isCI = isJust <$> getCI
diff --git a/src/CI/TH.hs b/src/CI/TH.hs
new file mode 100644
index 0000000..2a615d2
--- /dev/null
+++ b/src/CI/TH.hs
@@ -0,0 +1,22 @@
+module CI.TH
+  ( getVendors
+  ) where
+
+import qualified Data.Aeson                 as Aeson
+import qualified Language.Haskell.TH        as TH
+import qualified Language.Haskell.TH.Syntax as TH
+
+import qualified CI.Types                   as Types
+
+
+getVendors :: TH.Q TH.Exp
+getVendors = TH.runIO readVendors >>= TH.lift
+  where
+    vendorsPath = "res/vendors.json"
+
+    readVendors :: IO [Types.Vendor]
+    readVendors = do
+      vendors <- Aeson.eitherDecodeFileStrict' vendorsPath
+      case vendors of
+        Left e  -> fail $ "parsing vendors.json failed: " <> e
+        Right v -> return v
diff --git a/src/CI/Types.hs b/src/CI/Types.hs
new file mode 100644
index 0000000..02eec7c
--- /dev/null
+++ b/src/CI/Types.hs
@@ -0,0 +1,103 @@
+{-# LANGUAGE DeriveLift                 #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE LambdaCase                 #-}
+{-# LANGUAGE OverloadedStrings          #-}
+{-# LANGUAGE TemplateHaskell            #-}
+
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+module CI.Types
+  ( CI(..)
+  , Vendor(..)
+  , VendorEnv(..)
+  , EnvVarName(..)
+  , EnvVarValue(..)) where
+
+import           Data.Hashable              (Hashable)
+import           Data.HashMap.Strict        (HashMap)
+import           Data.Text                  (Text)
+import           Instances.TH.Lift          ()
+
+import qualified Data.Aeson                 as Aeson
+import qualified Data.Aeson.Casing          as Aeson
+import qualified Data.Aeson.TH              as Aeson
+import qualified Data.HashMap.Strict        as HashMap
+import qualified Data.Text                  as T
+import qualified Language.Haskell.TH.Syntax as TH
+
+
+data CI =
+    CI_APPVEYOR -- http://www.appveyor.com/
+  | CI_AZURE_PIPELINES -- https://azure.microsoft.com/en-us/services/devops/pipelines/
+  | CI_BAMBOO -- https://www.atlassian.com/software/bamboo/
+  | CI_BITBUCKET -- https://bitbucket.org/product/features/pipelines/
+  | CI_BITRISE -- https://www.bitrise.io/
+  | CI_BUDDY -- https://buddy.works/
+  | CI_BUILDKITE -- https://buildkite.com/
+  | CI_CIRCLE -- http://circleci.com/
+  | CI_CIRRUS -- https://cirrus-ci.org/
+  | CI_CODEBUILD -- https://aws.amazon.com/codebuild/
+  | CI_CODESHIP -- https://codeship.com/
+  | CI_DRONE -- https://drone.io/
+  | CI_DSARI -- https://github.com/rfinnie/dsari/
+  | CI_GITLAB -- https://about.gitlab.com/gitlab-ci/
+  | CI_GOCD -- https://www.go.cd/
+  | CI_HUDSON -- http://hudson-ci.org/
+  | CI_JENKINS -- https://jenkins-ci.org/
+  | CI_MAGNUM -- https://magnum-ci.com/
+  | CI_NETLIFY -- https://www.netlify.com/
+  | CI_NEVERCODE -- http://nevercode.io/
+  | CI_SAIL -- https://sail.ci/
+  | CI_SEMAPHORE -- https://semaphoreci.com/
+  | CI_SHIPPABLE -- https://www.shippable.com/
+  | CI_SOLANO -- https://www.solanolabs.com/
+  | CI_STRIDER -- https://strider-cd.github.io/
+  | CI_TASKCLUSTER -- http://docs.taskcluster.net/
+  | CI_TEAMCITY -- https://www.jetbrains.com/teamcity/
+  | CI_TRAVIS -- http://travis-ci.org/
+  | CI_UNKNOWN_VENDOR
+  deriving (Eq, Show, TH.Lift)
+
+$(Aeson.deriveJSON
+  Aeson.defaultOptions { Aeson.constructorTagModifier = drop $ T.length "CI_" }
+  ''CI)
+
+instance (TH.Lift k, TH.Lift v) => TH.Lift (HashMap k v) where
+  lift hashMap = [|HashMap.fromList $(TH.lift $ HashMap.toList hashMap)|]
+
+newtype EnvVarName = EnvVarName { unEnvVarName :: Text }
+  deriving (Eq, Hashable, Show, Aeson.FromJSON, Aeson.FromJSONKey, Aeson.ToJSON
+          , Aeson.ToJSONKey, TH.Lift)
+
+newtype EnvVarValue = EnvVarValue { unEnvVarValue :: Text }
+  deriving (Eq, Show, Aeson.FromJSON, Aeson.ToJSON, TH.Lift)
+
+data VendorEnv = VendorEnvString !EnvVarName
+               | VendorEnvList ![EnvVarName]
+               | VendorEnvObject !(HashMap EnvVarName EnvVarValue)
+  deriving (Eq, Show, TH.Lift)
+
+instance Aeson.FromJSON VendorEnv where
+  parseJSON val = case val of
+    Aeson.String _ -> VendorEnvString <$> Aeson.parseJSON val
+    Aeson.Array _ -> VendorEnvList <$> Aeson.parseJSON val
+    Aeson.Object _ -> VendorEnvObject <$> Aeson.parseJSON val
+    _ -> fail
+      "expected String, List[String], or Map[String, String] in vendor env"
+
+instance Aeson.ToJSON VendorEnv where
+  toJSON val = case val of
+    VendorEnvString name   -> Aeson.toJSON name
+    VendorEnvList list     -> Aeson.toJSON list
+    VendorEnvObject object -> Aeson.toJSON object
+
+newtype VendorName = VendorName { unVendorName :: Text }
+  deriving (Eq, Show, Aeson.FromJSON, Aeson.ToJSON, TH.Lift)
+
+data Vendor = Vendor { vendorName     :: !VendorName
+                     , vendorConstant :: !CI
+                     , vendorEnv      :: !VendorEnv
+                     }
+  deriving (Eq, Show, TH.Lift)
+
+$(Aeson.deriveJSON (Aeson.aesonPrefix Aeson.snakeCase) ''Vendor)
diff --git a/stack.yaml b/stack.yaml
new file mode 100644
index 0000000..d56f56d
--- /dev/null
+++ b/stack.yaml
@@ -0,0 +1,64 @@
+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+#
+# The location of a snapshot can be provided as a file or url. Stack assumes
+# a snapshot provided as a file might change, whereas a url resource does not.
+#
+# resolver: ./custom-snapshot.yaml
+# resolver: https://example.com/snapshots/2018-01-01.yaml
+resolver: lts-13.25
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#  subdirs:
+#  - auto-update
+#  - wai
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver
+# using the same syntax as the packages field.
+# (e.g., acme-missiles-0.3)
+# extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.9"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor