diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..43645ff
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+/git-pre-commit-hook
diff --git a/blacklist.go b/blacklist.go
new file mode 100644
index 0000000..0b9c996
--- /dev/null
+++ b/blacklist.go
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"bufio"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/logrusorgru/aurora"
+)
+
+func blacklisted() bool {
+	bl, err := blacklistedAux()
+	switch {
+	case err != nil:
+		Warn("failed to check blacklist: ", aurora.Red(err))
+		return true
+	case bl:
+		Warn("skipping git-commit hooks in blacklisted repo")
+		return true
+	default:
+		return false
+	}
+}
+
+func blacklistedAux() (bool, error) {
+	// open the user's blacklist file (and skip if ENOENT)
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return true, err
+	}
+
+	f, err := os.Open(filepath.Join(home,
+		"git/hooks/pre-commit-blacklist"))
+	switch {
+	case os.IsNotExist(err):
+		return false, nil
+	case err != nil:
+		return true, err
+	}
+
+	// we're called from the root of the git repo
+	cwd, err := os.Getwd()
+	if err != nil {
+		return true, err
+	}
+
+	// see if it matches
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		// get a line, stripping comments / spaces / blank lines
+		bl := scanner.Text()
+		if pos := strings.IndexRune(bl, '#'); pos != -1 {
+			bl = bl[:pos]
+		}
+		bl = strings.TrimSpace(bl)
+		if bl == "" {
+			continue
+		}
+
+		// we know bl[0] can be dereferenced
+		switch bl[0] {
+		case '*':
+			return strings.HasSuffix(cwd, bl[1:]), nil
+
+		case '~':
+			return cwd == home+bl[1:], nil
+
+		default:
+			return cwd == bl, nil
+		}
+	}
+	if scanner.Err() != nil {
+		return false, scanner.Err()
+	}
+
+	return false, nil
+}
diff --git a/check_gofmt.go b/check_gofmt.go
new file mode 100644
index 0000000..76b3ffd
--- /dev/null
+++ b/check_gofmt.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"github.com/logrusorgru/aurora"
+)
+
+// goFmt checks for bad formatting. It uses the "goimports" command. As of
+// 2020-02, the command "goimports ." recurses and ignores module boundaries and
+// non-go directories. It can therefore be run from the root of the git repo.
+func goFmt() error {
+	// execute goimports
+	wbuf := bytes.NewBuffer(nil)
+	cmd := exec.Command("goimports", "-l", ".")
+	cmd.Stdout = wbuf
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		// non-zero return code = program error (not bad formatting)
+		return fmt.Errorf("%s: %v", aurora.Blue("goimports -l"), aurora.Red(err))
+	}
+
+	// iterate over list of changed files, may be empty
+	var (
+		scanner = bufio.NewScanner(wbuf)
+		werr    strings.Builder
+		ok      = true
+	)
+	fmt.Fprintln(&werr, aurora.Red("The following files need reformatting:"))
+	for scanner.Scan() {
+		// ignore generated .pb.go files
+		if strings.HasSuffix(scanner.Text(), ".pb.go") {
+			continue
+		}
+
+		ok = false
+		werr.WriteByte('\t')
+		werr.WriteString(scanner.Text())
+		werr.WriteByte('\n')
+	}
+
+	if ok {
+		return nil
+	}
+	return errors.New(werr.String())
+}
diff --git a/check_govet.go b/check_govet.go
new file mode 100644
index 0000000..88897ae
--- /dev/null
+++ b/check_govet.go
@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	"github.com/logrusorgru/aurora"
+)
+
+// goVet executes "go vet" recursively for each module in the git repo. As of
+// go 1.13, "go vet ./..." is required to recurse but does not straddle
+// module boundaries. It must be run in a valid package directory. It is
+// significantly faster than running individual "go vet ." in each dir.
+func goVet() error {
+	return filepath.Walk(".", goVetW)
+}
+
+func goVetW(path string, info os.FileInfo, err error) error {
+	switch {
+	case err != nil:
+		return err
+	case info.Mode().IsDir() && strings.HasPrefix(info.Name(), "."):
+		return filepath.SkipDir
+	case info.Mode().IsRegular() && info.Name() == "go.mod":
+		dir := filepath.Dir(path)
+		Info(" running %q in %s", aurora.Blue("go vet"), aurora.Green(dir))
+		cmd := exec.Command("go", "vet", "./...")
+		cmd.Dir = path
+		op, err := cmd.CombinedOutput()
+		switch {
+		case len(op) > 0 && err != nil:
+			return fmt.Errorf("go vet failed: %s\n%s\n", aurora.Red(err), op)
+		case len(op) > 0:
+			return fmt.Errorf("%s:\n%s\n", aurora.Red("go vet reports"), op)
+		case err != nil:
+			return err
+		}
+	}
+	return nil
+}
diff --git a/check_largefiles.go b/check_largefiles.go
new file mode 100644
index 0000000..8d711cb
--- /dev/null
+++ b/check_largefiles.go
@@ -0,0 +1,32 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/logrusorgru/aurora"
+)
+
+const (
+	largeFileLimit = 1 << 20 // 1MiB
+)
+
+func checkLargeFiles() error {
+	return filepath.Walk(".", checkLargeFilesW)
+}
+
+func checkLargeFilesW(path string, info os.FileInfo, err error) error {
+	switch {
+	case err != nil:
+		return err
+	case info.Size() > largeFileLimit:
+		return fmt.Errorf("committing large file: %s (%d bytes)",
+			aurora.Red(path), info.Size())
+	case info.IsDir() && strings.HasPrefix(info.Name(), "."):
+		return filepath.SkipDir
+	default:
+		return nil
+	}
+}
diff --git a/git_stash.go b/git_stash.go
new file mode 100644
index 0000000..462fade
--- /dev/null
+++ b/git_stash.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+)
+
+var gitStashName string
+
+func gitStashPush() {
+	// create a temporary file that _ensures_ we have something to
+	// "git stash push". Without this, if all changes were staged, then
+	// "git stash push" would be a no-op, with exit code 0, and the
+	// final "git stash pop" would erroneously pop whatever the user had
+	// stashed themselves.
+	f, err := ioutil.TempFile(".", "git-pre-commit-hook-stash.")
+	if err != nil {
+		Err("failed to create temporary file: %v", err)
+	}
+	gitStashName = f.Name()
+	f.Close()
+
+	// perform git stash
+	cmd := exec.Command("git", "stash", "save",
+		"--keep-index", // don't stash staged changes
+		"--quiet",
+		"--include-untracked", // ignores new unstaged files
+	)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err = cmd.Run(); err != nil {
+		Err("failed to run git stash: %v", err)
+	}
+}
+
+func gitStashPop() {
+	defer os.Remove(gitStashName)
+	cmd := exec.Command("git", "stash", "pop", "--quiet")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		Err("failed to run git stash pop: %v", err)
+	}
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..29dd091
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,5 @@
+module src.lwithers.me.uk/go/git-pre-commit-hook
+
+go 1.13
+
+require github.com/logrusorgru/aurora v0.0.0-20200102142835-e9ef32dff381
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..6823f4b
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/logrusorgru/aurora v0.0.0-20200102142835-e9ef32dff381 h1:bqDmpDG49ZRnB5PcgP0RXtQvnMSgIF14M7CBd2shtXs=
+github.com/logrusorgru/aurora v0.0.0-20200102142835-e9ef32dff381/go.mod h1:7rIyQOR62GCctdiQpZ/zOJlFyk6y+94wXzv6RNZgaR4=
diff --git a/has_go.go b/has_go.go
new file mode 100644
index 0000000..5d6aaf2
--- /dev/null
+++ b/has_go.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/logrusorgru/aurora"
+)
+
+func hasGo() bool {
+	h, err := hasGoAux(".", 3)
+	if err != nil {
+		Warn("error scanning directory for go.mod: %v", aurora.Red(err))
+		return false
+	}
+	return h
+}
+
+func hasGoAux(dir string, depth int) (bool, error) {
+	fi, err := ioutil.ReadDir(dir)
+	if err != nil {
+		return false, err
+	}
+
+	var dirs []string
+
+	for _, f := range fi {
+		switch {
+		case f.Name()[0] == '.':
+			// do nothing
+
+		case f.IsDir():
+			dirs = append(dirs, f.Name())
+
+		case f.Name() == "go.mod":
+			return true, nil
+		}
+	}
+
+	if depth == 0 {
+		return false, nil
+	}
+	depth--
+
+	for _, subdir := range dirs {
+		h, err := hasGoAux(filepath.Join(dir, subdir), depth)
+		if h || err != nil {
+			return h, err
+		}
+	}
+
+	return false, nil
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..711be36
--- /dev/null
+++ b/main.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func main() {
+	if blacklisted() || !hasGo() {
+		os.Exit(0)
+	}
+
+	var exitCode int
+
+	Info("Stashing unstaged changes…")
+	gitStashPush()
+
+	Info("Checking for large files…")
+	if err := checkLargeFiles(); err != nil {
+		fmt.Println(err)
+		exitCode = 1
+	}
+
+	Info("Running goimports…")
+	if err := goFmt(); err != nil {
+		fmt.Println(err)
+		exitCode = 1
+	}
+
+	Info("Running go vet…")
+	if err := goVet(); err != nil {
+		fmt.Println(err)
+		exitCode = 1
+	}
+
+	Info("Restoring unstaged changes…")
+	gitStashPop()
+	os.Exit(exitCode)
+}
diff --git a/output.go b/output.go
new file mode 100644
index 0000000..6a004ba
--- /dev/null
+++ b/output.go
@@ -0,0 +1,28 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/logrusorgru/aurora"
+)
+
+var (
+	title    = aurora.Blue("[~/git/hooks/bin/pre-commit]")
+	info     = aurora.Blue("INFO")
+	warning  = aurora.Yellow("WARN")
+	errorStr = aurora.Red("ERR ")
+)
+
+func Info(format string, args ...interface{}) {
+	fmt.Fprintln(os.Stderr, title, info, fmt.Sprintf(format, args...))
+}
+
+func Warn(format string, args ...interface{}) {
+	fmt.Fprintln(os.Stderr, title, warning, fmt.Sprintf(format, args...))
+}
+
+func Err(format string, args ...interface{}) {
+	fmt.Fprintln(os.Stderr, title, errorStr, fmt.Sprintf(format, args...))
+	os.Exit(1)
+}