diff --git a/docs/development/plugin-triggers.md b/docs/development/plugin-triggers.md
index 61d05c603..fa8505b9b 100644
--- a/docs/development/plugin-triggers.md
+++ b/docs/development/plugin-triggers.md
@@ -143,6 +143,24 @@ set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
 # TODO
 ```
 
+### `builder-detect`
+
+- Description: Allows overriding the auto-detected `herokuish` builder in favor of a custom one. Dockerfile gets lowest builder precedence.
+- Invoked by: `dokku deploy`
+- Arguments: `$APP` `$SOURCECODE_WORK_DIR`
+- Example:
+
+```shell
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x
+APP="$1"; SOURCECODE_WORK_DIR="$2"
+
+if [[ -f "$SOURCECODE_WORK_DIR/project.toml" ]]; then
+  echo -n "cnb"
+fi
+```
+
 ### `builder-create-dokku-image`
 
 - Description: Allows modification of the configured dokku-image
diff --git a/plugins/20_events/builder-detect b/plugins/20_events/builder-detect
new file mode 120000
index 000000000..5178a749f
--- /dev/null
+++ b/plugins/20_events/builder-detect
@@ -0,0 +1 @@
+hook
\ No newline at end of file
diff --git a/plugins/builder-cnb/builder-detect b/plugins/builder-cnb/builder-detect
new file mode 100755
index 000000000..65678e55d
--- /dev/null
+++ b/plugins/builder-cnb/builder-detect
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+source "$PLUGIN_AVAILABLE_PATH/config/functions"
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+trigger-builder-cnb-builder-detect() {
+  declare desc="builder-cnb builder-detect plugin trigger"
+  declare trigger="builder-detect"
+  declare APP="$1" SOURCECODE_WORK_DIR="$2"
+
+  if [[ -f "$SOURCECODE_WORK_DIR/project.toml" ]]; then
+    echo "cnb"
+    return
+  fi
+
+  if [[ "$(config_get "$APP" DOKKU_CNB_EXPERIMENTAL || true)" == "1" ]]; then
+    echo "cnb"
+    return
+  fi
+}
+
+trigger-builder-cnb-builder-detect "$@"
diff --git a/plugins/builder-dockerfile/builder-detect b/plugins/builder-dockerfile/builder-detect
new file mode 100755
index 000000000..1def88e9f
--- /dev/null
+++ b/plugins/builder-dockerfile/builder-detect
@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+source "$PLUGIN_AVAILABLE_PATH/config/functions"
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+trigger-builder-dockerfile-builder-detect() {
+  declare desc="builder-dockerfile builder-detect plugin trigger"
+  declare trigger="builder-detect"
+  declare APP="$1" SOURCECODE_WORK_DIR="$2"
+
+  # buildpacks always win against dockerfile detection
+  # that includes cnb
+  if [[ -f "$SOURCECODE_WORK_DIR/project.toml" ]]; then
+    return
+  fi
+
+  # buildpacks always win against dockerfile detection
+  # that includes cnb
+  if [[ "$(config_get "$APP" DOKKU_CNB_EXPERIMENTAL || true)" == "1" ]]; then
+    echo "cnb"
+    return
+  fi
+
+  if [[ -f "$SOURCECODE_WORK_DIR/Dockerfile" ]]; then
+    echo "dockerfile"
+    return
+  fi
+}
+
+trigger-builder-dockerfile-builder-detect "$@"
diff --git a/plugins/builder-herokuish/builder-detect b/plugins/builder-herokuish/builder-detect
new file mode 100755
index 000000000..7ee618691
--- /dev/null
+++ b/plugins/builder-herokuish/builder-detect
@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+source "$PLUGIN_AVAILABLE_PATH/builder-herokuish/functions"
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+trigger-builder-herokuish-builder-detect() {
+  declare desc="builder-herokuish builder-detect plugin trigger"
+  declare trigger="builder-detect"
+  declare APP="$1" SOURCECODE_WORK_DIR="$2"
+
+  if fn-has-buildpacks-file "$SOURCECODE_WORK_DIR"; then
+    echo "herokuish"
+    return
+  fi
+
+  if fn-has-buildpack-dotenv "$SOURCECODE_WORK_DIR"; then
+    echo "herokuish"
+    return
+  fi
+
+  if fn-has-buildpack-env "$APP"; then
+    echo "herokuish"
+    return
+  fi
+}
+
+trigger-builder-herokuish-builder-detect "$@"
diff --git a/plugins/builder-herokuish/functions b/plugins/builder-herokuish/functions
new file mode 100755
index 000000000..8452214a1
--- /dev/null
+++ b/plugins/builder-herokuish/functions
@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+source "$PLUGIN_AVAILABLE_PATH/config/functions"
+set -eo pipefail
+[[ $DOKKU_TRACE ]] && set -x
+
+fn-has-buildpacks-file() {
+  declare SOURCECODE_WORK_DIR="$1"
+
+  if [[ -f "$SOURCECODE_WORK_DIR/.buildpacks" ]]; then
+    return 0
+  fi
+
+  return 1
+}
+
+fn-has-buildpack-dotenv() {
+  declare SOURCECODE_WORK_DIR="$1"
+
+  if [[ ! -f "$SOURCECODE_WORK_DIR/.env" ]]; then
+    return 1
+  fi
+
+  if grep -q BUILDPACK_URL "$SOURCECODE_WORK_DIR/.env"; then
+    return 0
+  fi
+
+  return 1
+}
+
+fn-has-buildpack-env() {
+  declare APP="$1"
+
+  if [[ -n $(config_get "$APP" BUILDPACK_URL || true) ]]; then
+    return 0
+  fi
+
+  return 1
+}
diff --git a/plugins/git/functions b/plugins/git/functions
index 114c28971..a67b795e1 100755
--- a/plugins/git/functions
+++ b/plugins/git/functions
@@ -49,18 +49,15 @@ git_build_app_repo() {
 git_trigger_build() {
   declare desc="triggers the actual build process for a given app within a directory at a particular revision"
   declare APP="$1" TMP_WORK_DIR="$2" REV="$3"
+  local BUILDER
 
   plugn trigger post-extract "$APP" "$TMP_WORK_DIR" "$REV"
-  if [[ -f Dockerfile ]] && [[ "$(
-    [[ -f .env ]] && grep -q BUILDPACK_URL .env
-    echo $?
-  )" != "0" ]] && [[ ! -f ".buildpacks" ]] && [[ -z $(config_get "$APP" BUILDPACK_URL || true) ]]; then
-    plugn trigger pre-receive-app "$APP" "dockerfile" "$TMP_WORK_DIR" "$REV"
-    dokku_receive "$APP" "dockerfile" "$TMP_WORK_DIR"
-  else
-    plugn trigger pre-receive-app "$APP" "herokuish" "$TMP_WORK_DIR" "$REV"
-    dokku_receive "$APP" "herokuish" "$TMP_WORK_DIR"
-  fi
+
+  BUILDER="$(plugn trigger builder-detect "$APP" "$TMP_WORK_DIR" | tail -n1 || true)"
+  [[ -z "$BUILDER" ]] && BUILDER="herokuish"
+
+  plugn trigger pre-receive-app "$APP" "$BUILDER" "$TMP_WORK_DIR" "$REV"
+  dokku_receive "$APP" "$BUILDER" "$TMP_WORK_DIR"
 }
 
 git_deploy_branch() {
diff --git a/plugins/tar/functions b/plugins/tar/functions
index 9a8302c99..c95d29303 100755
--- a/plugins/tar/functions
+++ b/plugins/tar/functions
@@ -41,18 +41,15 @@ tar_build() {
 tar_trigger_build() {
   declare desc="triggers the actual build process for a given app within a directory at a particular revision"
   declare APP="$1" TMP_WORK_DIR="$2" REV="$3"
+  local BUILDER
 
   plugn trigger post-extract "$APP" "$TMP_WORK_DIR" "$REV"
-  if [[ -f Dockerfile ]] && [[ "$(
-    [[ -f .env ]] && grep -q BUILDPACK_URL .env
-    echo $?
-  )" != "0" ]] && [[ ! -f ".buildpacks" ]] && [[ -z $(config_get "$APP" BUILDPACK_URL || true) ]]; then
-    plugn trigger pre-receive-app "$APP" "dockerfile" "$TMP_WORK_DIR" "$REV"
-    dokku_receive "$APP" "dockerfile" "$TMP_WORK_DIR"
-  else
-    plugn trigger pre-receive-app "$APP" "herokuish" "$TMP_WORK_DIR" "$REV"
-    dokku_receive "$APP" "herokuish" "$TMP_WORK_DIR"
-  fi
+
+  BUILDER="$(plugn trigger builder-detect "$APP" "$TMP_WORK_DIR" | tail -n1 || true)"
+  [[ -z "$BUILDER" ]] && BUILDER="herokuish"
+
+  plugn trigger pre-receive-app "$APP" "$BUILDER" "$TMP_WORK_DIR" "$REV"
+  dokku_receive "$APP" "$BUILDER" "$TMP_WORK_DIR"
 }
 
 cmd-tar-in() {
diff --git a/tests/unit/builder.bats b/tests/unit/builder.bats
new file mode 100644
index 000000000..d6f620c4e
--- /dev/null
+++ b/tests/unit/builder.bats
@@ -0,0 +1,121 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+setup() {
+  create_app
+}
+
+teardown() {
+  destroy_app
+}
+
+@test "(builder) builder-detect [cnb]" {
+  local TMP=$(mktemp -d "/tmp/dokku.me.XXXXX")
+  trap 'popd &>/dev/null || true; rm -rf "$TMP"' INT TERM
+
+  # test project.toml
+  run touch "$TMP/project.toml"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "dokku plugin:trigger builder-detect $TEST_APP $TMP | tail -n1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "cnb"
+
+  sudo rm -rf $TMP/*
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  # test DOKKU_CNB_EXPERIMENTAL env var
+  run /bin/bash -c "dokku config:set $TEST_APP DOKKU_CNB_EXPERIMENTAL=1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "dokku plugin:trigger builder-detect $TEST_APP $TMP | tail -n1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "cnb"
+}
+
+@test "(builder) builder-detect [dockerfile]" {
+  local TMP=$(mktemp -d "/tmp/dokku.me.XXXXX")
+  trap 'popd &>/dev/null || true; rm -rf "$TMP"' INT TERM
+
+  run touch "$TMP/Dockerfile"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "dokku plugin:trigger builder-detect $TEST_APP $TMP | tail -n1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "dockerfile"
+}
+
+@test "(builder) builder-detect [herokuish]" {
+  local TMP=$(mktemp -d "/tmp/dokku.me.XXXXX")
+  trap 'popd &>/dev/null || true; rm -rf "$TMP"' INT TERM
+
+  touch "$TMP/Dockerfile"
+
+  # test buildpacks
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "touch $TMP/.buildpacks"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "dokku plugin:trigger builder-detect $TEST_APP $TMP | tail -n1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "herokuish"
+
+  sudo rm -rf $TMP/*
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  # test .env
+  run /bin/bash -c "echo BUILDPACK_URL=null > $TMP/.env"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "dokku plugin:trigger builder-detect $TEST_APP $TMP | tail -n1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "herokuish"
+
+  sudo rm -rf $TMP/*
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  # test BUILDPACK_URL env var
+  run /bin/bash -c "dokku config:set $TEST_APP BUILDPACK_URL=null"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  chown -R dokku:dokku "$TMP"
+  run /bin/bash -c "dokku plugin:trigger builder-detect $TEST_APP $TMP | tail -n1"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "herokuish"
+}