diff --git a/README.md b/README.md
index 94a08be20..3f19dc075 100755
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ class Hello : CliktCommand() {
 
     override fun run() {
         for (i in 1..count) {
-            TermUi.echo("Hello $name!")
+            echo("Hello $name!")
         }
     }
 }
diff --git a/build.gradle b/build.gradle
index dba6d03db..f53d3307a 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,5 +1,5 @@
 buildscript {
-    ext.kotlin_version = '1.2.51'
+    ext.kotlin_version = '1.2.61'
 
     repositories {
         mavenCentral()
@@ -30,8 +30,8 @@ subprojects {
         compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
 
         testImplementation 'junit:junit:4.12'
-        testImplementation 'io.kotlintest:kotlintest-assertions:3.1.7'
-        testImplementation 'com.github.stefanbirkner:system-rules:1.17.0'
+        testImplementation 'io.kotlintest:kotlintest-assertions:3.1.9'
+        testImplementation 'com.github.stefanbirkner:system-rules:1.18.0'
         testImplementation 'com.google.jimfs:jimfs:1.1'
     }
 
diff --git a/docs/advanced.md b/docs/advanced.md
index bcef037b2..584e7f162 100644
--- a/docs/advanced.md
+++ b/docs/advanced.md
@@ -29,7 +29,7 @@ class Repo : NoRunCliktCommand() {
 class Commit: CliktCommand() {
     val message by option("-m").default("")
     override fun run() {
-        TermUi.echo("Committing with message: $message")
+        echo("Committing with message: $message")
     }
 }
 
@@ -75,13 +75,13 @@ class Tool : CliktCommand() {
 
 class Foo: CliktCommand() {
     override fun run() {
-        TermUi.echo("Running Foo")
+        echo("Running Foo")
     }
 }
 
 class Bar: CliktCommand() {
     override fun run() {
-        TermUi.echo("Running Bar")
+        echo("Running Bar")
     }
 }
 
@@ -111,7 +111,7 @@ class Hello : CliktCommand() {
     }
 
     val name by option()
-    override fun run() = TermUi.echo("Hello $name!")
+    override fun run() = echo("Hello $name!")
 }
 ```
 
@@ -119,3 +119,38 @@ class Hello : CliktCommand() {
 $ ./hello --NAME=Foo
 Hello Foo!
 ```
+
+## Replacing stdin and stdout
+
+By default, functions like [`CliktCommand.main`](api/clikt/com.github.ajalt.clikt.core/-clikt-command/main.html)
+and [`option().prompt()`](api/clikt/com.github.ajalt.clikt.parameters.options/prompt.html)
+read from `System.in` and write to `System.out`. If you want to use
+clikt in an environment where the standard streams aren't available, you
+can set your own implementation of [`CliktConsole`](api/clikt/com.github.ajalt.clikt.output/-clikt-console/index.html)
+when [customizing the command context](commands.md#customizing-contexts).
+
+```kotlin
+object MyConsole : CliktConsole {
+    override fun promptForLine(prompt: String, hideInput: Boolean): String? {
+        MyOutputStream.write(prompt)
+        return if (hideInput) MyInputStream.readPassword()
+        else MyInputStream.readLine()
+    }
+
+    override fun print(text: String, error: Boolean) {
+        if (error) MyOutputStream.writeError(prompt)
+        else MyOutputStream.write(prompt)
+    }
+
+    override val lineSeparator: String get() = "\n"
+}
+
+class CustomCLI : CliktCommand() {
+    init { context { this.console = MyConsole } }
+    override fun run() {}
+}
+```
+
+If you are using
+[`TermUI`](api/clikt/com.github.ajalt.clikt.output/-term-ui/index.html)
+directly, you can also pass your custom console as an argument.
diff --git a/docs/arguments.md b/docs/arguments.md
index 07ae9ce0c..3b7e05945 100644
--- a/docs/arguments.md
+++ b/docs/arguments.md
@@ -14,7 +14,7 @@ provided on the command line.
 class Hello : CliktCommand() {
     val name by argument()
     override fun run() {
-        TermUi.echo("Hello $name!")
+        echo("Hello $name!")
     }
 }
 ```
@@ -69,7 +69,7 @@ class Copy : CliktCommand() {
     val source by argument().file(exists = true).multiple()
     val dest by argument().file(fileOkay = false)
     override fun run() {
-        TermUi.echo("Copying files $source to $dest")
+        echo("Copying files $source to $dest")
     }
 }
 ```
@@ -98,7 +98,7 @@ class Touch : CliktCommand() {
     val verbose by option().flag()
     val files by argument().multiple()
     override fun run() {
-        if (verbose) TermUi.echo(files.joinToString("\n"))
+        if (verbose) echo(files.joinToString("\n"))
     }
 }
 ```
diff --git a/docs/commands.md b/docs/commands.md
index 088863c37..43b0ddd0b 100644
--- a/docs/commands.md
+++ b/docs/commands.md
@@ -19,13 +19,13 @@ the help page is printed and `run` is not called.
 class Tool : CliktCommand() {
     val verbose by option().flag("--no-verbose")
     override fun run() {
-        TermUi.echo("Verbose mode is ${if (verbose) "on" else "off"}")
+        echo("Verbose mode is ${if (verbose) "on" else "off"}")
     }
 }
 
 class Execute : CliktCommand() {
     override fun run() {
-        TermUi.echo("executing")
+        echo("executing")
     }
 }
 
@@ -66,7 +66,7 @@ class Tool : CliktCommand() {
 
 class Execute : CliktCommand(name = "RUN-ME") {
     override fun run() {
-        TermUi.echo("executing")
+        echo("executing")
     }
 }
 
@@ -176,7 +176,7 @@ class Tool : CliktCommand() {
 class Execute : CliktCommand() {
     val config by requireObject<Map<String, String>>()
     override fun run() {
-        TermUi.echo("Verbose mode is ${config["VERBOSE"]}")
+        echo("Verbose mode is ${config["VERBOSE"]}")
     }
 }
 
@@ -210,16 +210,16 @@ one.
 class Tool : CliktCommand(invokeWithoutSubcommand = true) {
     override fun run() {
         if (context.invokedSubcommand == null) {
-            TermUi.echo("invoked without a subcommand")
+            echo("invoked without a subcommand")
         } else {
-            TermUi.echo("about to run ${context.invokedSubcommand!!.commandName}")
+            echo("about to run ${context.invokedSubcommand!!.commandName}")
         }
     }
 }
 
 class Execute : CliktCommand() {
     override fun run() {
-        TermUi.echo("running subcommand")
+        echo("running subcommand")
     }
 }
 
diff --git a/docs/documenting.md b/docs/documenting.md
index f0ef564b8..b061d7966 100644
--- a/docs/documenting.md
+++ b/docs/documenting.md
@@ -21,7 +21,7 @@ class Hello : CliktCommand(help = """
 
     val count by option("-c", "--count", help = "number of greetings").int().default(1)
     val name by argument()
-    override fun run() = repeat(count) { TermUi.echo("Hello $name!") }
+    override fun run() = repeat(count) { echo("Hello $name!") }
 }
 ```
 
diff --git a/docs/index.md b/docs/index.md
index cd1563e02..d9dd8e784 100755
--- a/docs/index.md
+++ b/docs/index.md
@@ -1,3 +1,7 @@
+---
+title: 'Clikt: Simple, powerful command line parser for Kotlin'
+---
+
 <div align="center" style="margin-bottom:42px;max-width:700px">
     <img alt="wordmark" src="img/wordmark.svg" />
 </div>
@@ -27,7 +31,7 @@ class Hello : CliktCommand() {
 
     override fun run() {
         for (i in 1..count) {
-            TermUi.echo("Hello $name!")
+            echo("Hello $name!")
         }
     }
 }
diff --git a/docs/options.md b/docs/options.md
index b4d5e9c6d..2de84b55d 100644
--- a/docs/options.md
+++ b/docs/options.md
@@ -13,7 +13,7 @@ will return the value of the last occurrence of the option.
 class Hello: CliktCommand() {
     val name by option(help="your name")
     override fun run() {
-        TermUi.echo("Hello, $name!")
+        echo("Hello, $name!")
     }
 }
 ```
@@ -38,7 +38,7 @@ You can also specify any number of names for an option manually:
 class Hello: CliktCommand() {
     val name by option("-n", "--name", help="your name")
     override fun run() {
-        TermUi.echo("Hello, $name!")
+        echo("Hello, $name!")
     }
 }
 ```
@@ -121,7 +121,7 @@ on the command line. You can instead return a default value with [`default`](api
 class Pow : CliktCommand() {
     val exp by option("-e", "--exp").double().default(1.0)
     override fun run() {
-        TermUi.echo("2 ^ $exp = ${Math.pow(2.0, exp)}")
+        echo("2 ^ $exp = ${Math.pow(2.0, exp)}")
     }
 }
 ```
@@ -167,9 +167,9 @@ class Geometry : CliktCommand() {
     val cube by option().int().triple()
     val tesseract by option().int().transformValues(4) { Quad(it[0], it[1], it[2], it[3]) }
     override fun run() {
-        TermUi.echo("Square has dimensions ${square?.toList()?.joinToString("x")}")
-        TermUi.echo("Cube has dimensions ${cube?.toList()?.joinToString("x")}")
-        TermUi.echo("Tesseract has dimensions ${tesseract?.toList()?.joinToString("x")}")
+        echo("Square has dimensions ${square?.toList()?.joinToString("x")}")
+        echo("Cube has dimensions ${cube?.toList()?.joinToString("x")}")
+        echo("Tesseract has dimensions ${tesseract?.toList()?.joinToString("x")}")
     }
 }
 ```
@@ -199,7 +199,7 @@ list will be empty (or you can specify a list to use).
 class Commit : CliktCommand() {
     val message by option("-m").multiple()
     override fun run() {
-        TermUi.echo(message.joinToString("\n"))
+        echo(message.joinToString("\n"))
     }
 }
 ```
@@ -235,7 +235,7 @@ previously.
 class Cli : CliktCommand() {
     val flag by option("--on", "-o").flag("--off", "-O", default = false)
     override fun run() {
-        TermUi.echo(flag)
+        echo(flag)
     }
 }
 ```
@@ -262,7 +262,7 @@ class Cli : CliktCommand() {
     val flagB by option("-b").flag()
     val foo by option("-f")
     override fun run() {
-        TermUi.echo("$flagA $flagB $foo")
+        echo("$flagA $flagB $foo")
     }
 }
 ```
@@ -284,7 +284,7 @@ on the command line. You can use [`counted`](api/clikt/com.github.ajalt.clikt.pa
 class Log : CliktCommand() {
     val verbosity by option("-v").counted()
     override fun run() {
-        TermUi.echo("Verbosity level: $verbosity")
+        echo("Verbosity level: $verbosity")
     }
 }
 ```
@@ -306,7 +306,7 @@ the names in the map replace any previously specified or inferred names.
 class Size : CliktCommand() {
     val size by option().switch("--large" to "large", "--small" to "small").default("unknown")
     override fun run() {
-        TermUi.echo("You picked size $size")
+        echo("You picked size $size")
     }
 }
 ```
@@ -327,7 +327,7 @@ values using [`choice`](api/clikt/com.github.ajalt.clikt.parameters.types/choice
 class Digest : CliktCommand() {
     val hash by option().choice("md5", "sha1")
     override fun run() {
-        TermUi.echo(hash)
+        echo(hash)
     }
 }
 ```
@@ -365,7 +365,7 @@ if one is not provided. Clikt can take care of this for you with the [`prompt`](
 class Hello : CliktCommand() {
     val name by option().prompt()
     override fun run() {
-        TermUi.echo("Hello $name")
+        echo("Hello $name")
     }
 }
 ```
@@ -396,7 +396,7 @@ passwords.
 class Login : CliktCommand() {
     val password by option().prompt(requireConfirmation = true, hideInput = true)
     override fun run() {
-        TermUi.echo("Your hidden password: $password")
+        echo("Your hidden password: $password")
     }
 }
 ```
@@ -491,7 +491,7 @@ To set the envvar name manually, pass the name to [`option`](api/clikt/com.githu
 class Hello : CliktCommand() {
     val name by option(envvar = "MY_NAME")
     override fun run() {
-        TermUi.echo("Hello $name")
+        echo("Hello $name")
     }
 }
 ```
@@ -524,7 +524,7 @@ class Hello : CliktCommand() {
     }
     val name by option()
     override fun run() {
-        TermUi.echo("Hello $name")
+        echo("Hello $name")
     }
 }
 ```
@@ -552,7 +552,7 @@ colons (`:`).
 class Hello : CliktCommand() {
     val names by option(envvar = "NAMES").multiple()
     override fun run() {
-        for (name in names) TermUi.echo("Hello $name")
+        for (name in names) echo("Hello $name")
     }
 }
 ```
@@ -577,7 +577,7 @@ For example, you can make a Windows-style interface with slashes:
 class Hello: CliktCommand() {
     val name by option("/name", help="your name")
     override fun run() {
-        TermUi.echo("Hello, $name!")
+        echo("Hello, $name!")
     }
 }
 ```
@@ -596,7 +596,7 @@ options:
 class Hello: CliktCommand() {
     val name by option("-name", help="your name")
     override fun run() {
-        TermUi.echo("Hello, $name!")
+        echo("Hello, $name!")
     }
 }
 ```
diff --git a/docs/parameters.md b/docs/parameters.md
index 8920a8716..b2305f08e 100644
--- a/docs/parameters.md
+++ b/docs/parameters.md
@@ -129,7 +129,7 @@ For example, you can create an option of type `BigDecimal` like this:
 ```kotlin
 class Cli: CliktCommand() {
     val opt by option().convert { it.toBigDecimal() }
-    override fun run() = TermUi.echo("opt=$opt")
+    override fun run() = echo("opt=$opt")
 }
 ```
 
@@ -154,7 +154,7 @@ class Cli: CliktCommand() {
     val opt by option(help="a real number").convert("FLOAT") {
         it.toBigDecimalOrNull() ?: fail("A real number is required")
     }
-    override fun run() = TermUi.echo("opt=$opt")
+    override fun run() = echo("opt=$opt")
 }
 ```
 
diff --git a/docs/quickstart.md b/docs/quickstart.md
index f4f7e9e2c..1a6964a5f 100644
--- a/docs/quickstart.md
+++ b/docs/quickstart.md
@@ -14,7 +14,7 @@ The simplest command with no parameters would look like this:
 ```kotlin
 class Hello: CliktCommand() {
     override fun run() {
-        TermUi.echo("Hello World!")
+        echo("Hello World!")
     }
 }
 
@@ -40,7 +40,7 @@ Options:
 
 ## Printing to Stdout and Stderr
 
-Why does this example use [TermUi.echo](api/clikt/com.github.ajalt.clikt.output/-term-ui/echo.html) instead of
+Why does this example use [echo](api/clikt/com.github.ajalt.clikt.core/-clikt-command/echo.html) instead of
 [println](https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.io/println.html)?
 Although `println` works, it can cause problems with multi-platform
 support. [echo](api/clikt/com.github.ajalt.clikt.output/-term-ui/echo.html) automatically translates line breaks into the line
@@ -62,13 +62,13 @@ class Database: CliktCommand() {
 
 class Init: CliktCommand(help="Initialize the database") {
     override fun run() {
-        TermUi.echo("Initialized the database.")
+        echo("Initialized the database.")
     }
 }
 
 class Drop: CliktCommand(help="Drop the database") {
     override fun run() {
-        TermUi.echo("Dropped the database.")
+        echo("Dropped the database.")
     }
 }
 
@@ -110,7 +110,7 @@ class Hello : CliktCommand() {
 
     override fun run() {
         for (i in 1..count) {
-            TermUi.echo("Hello $name!")
+            echo("Hello $name!")
         }
     }
 }
diff --git a/mkdocs.yml b/mkdocs.yml
index 5a69b72fc..fc57a4cff 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -84,6 +84,7 @@ nav:
   - 'Advanced Patterns':
     - 'Command Aliases': advanced.md
     - 'Token Normalization': advanced/#token-normalization
+    - 'Replacing stdin and stdout': advanced/#replacing-stdin-and-stdout
   - 'Utilities':
     - 'Launching Editors': utilities.md
     - 'Input Prompts': utilities/#input-prompts