diff --git a/cmd/dagger/cmd/common/common.go b/cmd/dagger/cmd/common/common.go
index a83560e8..712757f2 100644
--- a/cmd/dagger/cmd/common/common.go
+++ b/cmd/dagger/cmd/common/common.go
@@ -110,7 +110,7 @@ func FormatValue(val *compiler.Value) string {
 		return "dagger.#Secret"
 	}
 	if val.IsConcreteR() != nil {
-		return val.Cue().IncompleteKind().String()
+		return val.IncompleteKindString()
 	}
 	// value representation in Cue
 	valStr := fmt.Sprintf("%v", val.Cue())
@@ -121,7 +121,7 @@ func FormatValue(val *compiler.Value) string {
 // ValueDocString returns the value doc from the comment lines
 func ValueDocString(val *compiler.Value) string {
 	docs := []string{}
-	for _, c := range val.Cue().Doc() {
+	for _, c := range val.Doc() {
 		docs = append(docs, strings.TrimSpace(c.Text()))
 	}
 	doc := strings.Join(docs, " ")
diff --git a/cmd/dagger/cmd/doc.go b/cmd/dagger/cmd/doc.go
new file mode 100644
index 00000000..859ed897
--- /dev/null
+++ b/cmd/dagger/cmd/doc.go
@@ -0,0 +1,289 @@
+package cmd
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/fs"
+	"os"
+	"strings"
+	"text/tabwriter"
+	"unicode/utf8"
+
+	"cuelang.org/go/cue"
+	"github.com/rs/zerolog/log"
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"go.dagger.io/dagger/cmd/dagger/cmd/common"
+	"go.dagger.io/dagger/cmd/dagger/logger"
+	"go.dagger.io/dagger/compiler"
+	"go.dagger.io/dagger/environment"
+	"go.dagger.io/dagger/stdlib"
+	"golang.org/x/term"
+)
+
+const (
+	textFormat     = "txt"
+	markdownFormat = "md"
+	jsonFormat     = "json"
+	textPadding    = "    "
+)
+
+// types used for json generation
+
+type ValueJSON struct {
+	Name        string
+	Type        string
+	Description string
+}
+
+type FieldJSON struct {
+	Name        string
+	Description string
+	Inputs      []ValueJSON
+	Outputs     []ValueJSON
+}
+
+type PackageJSON struct {
+	Name        string
+	Description string
+	Fields      []FieldJSON
+}
+
+var docCmd = &cobra.Command{
+	Use:   "doc [PACKAGE | PATH]",
+	Short: "document a package",
+	Args:  cobra.ExactArgs(1),
+	PreRun: func(cmd *cobra.Command, args []string) {
+		// Fix Viper bug for duplicate flags:
+		// https://github.com/spf13/viper/issues/233
+		if err := viper.BindPFlags(cmd.Flags()); err != nil {
+			panic(err)
+		}
+	},
+	Run: func(cmd *cobra.Command, args []string) {
+		lg := logger.New()
+		ctx := lg.WithContext(cmd.Context())
+
+		format := viper.GetString("output")
+		if format != textFormat &&
+			format != markdownFormat &&
+			format != jsonFormat {
+			lg.Fatal().Msg("output must be either `txt`, `md` or `json`")
+		}
+
+		packageName := args[0]
+
+		val, err := loadCode(packageName)
+		if err != nil {
+			lg.Fatal().Err(err).Msg("cannot compile code")
+		}
+		PrintDoc(ctx, packageName, val, format)
+	},
+}
+
+func init() {
+	docCmd.Flags().StringP("output", "o", textFormat, "Output format (txt|md)")
+
+	if err := viper.BindPFlags(docCmd.Flags()); err != nil {
+		panic(err)
+	}
+}
+
+func mdEscape(s string) string {
+	escape := []string{"|", "<", ">"}
+	for _, c := range escape {
+		s = strings.ReplaceAll(s, c, `\`+c)
+	}
+	return s
+}
+
+func terminalTrim(msg string) string {
+	// If we're not running on a terminal, return the whole string
+	size, _, err := term.GetSize(1)
+	if err != nil {
+		return msg
+	}
+
+	// Otherwise, trim to fit half the terminal
+	size /= 2
+	for utf8.RuneCountInString(msg) > size {
+		msg = msg[0:len(msg)-4] + "…"
+	}
+	return msg
+}
+
+func formatLabel(name string, val *compiler.Value) string {
+	label := val.Path().String()
+	return strings.TrimPrefix(label, name+".")
+}
+
+func loadCode(packageName string) (*compiler.Value, error) {
+	sources := map[string]fs.FS{
+		stdlib.Path: stdlib.FS,
+	}
+
+	src, err := compiler.Build(sources, packageName)
+	if err != nil {
+		return nil, err
+	}
+
+	return src, nil
+}
+
+// printValuesText (text) formats an array of Values on stdout
+func printValuesText(libName string, values []*compiler.Value) {
+	w := tabwriter.NewWriter(os.Stdout, 0, 4, len(textPadding), ' ', 0)
+	fmt.Printf("\n%sInputs:\n", textPadding)
+	for _, i := range values {
+		docStr := terminalTrim(common.ValueDocString(i))
+		fmt.Fprintf(w, "\t\t%s\t%s\t%s\n",
+			formatLabel(libName, i), common.FormatValue(i), docStr)
+	}
+	w.Flush()
+}
+
+// printValuesMarkdown (markdown) formats an array of Values on stdout
+func printValuesMarkdown(libName string, values []*compiler.Value) {
+	w := tabwriter.NewWriter(os.Stdout, 0, 4, len(textPadding), ' ', 0)
+	fmt.Fprintf(w, "| Name\t| Type\t| Description    \t|\n")
+	fmt.Fprintf(w, "| -------------\t|:-------------:\t|:-------------:\t|\n")
+	for _, i := range values {
+		fmt.Fprintf(w, "|*%s*\t|``%s``\t|%s\t|\n",
+			formatLabel(libName, i),
+			mdEscape(common.FormatValue(i)),
+			mdEscape(common.ValueDocString(i)))
+	}
+	fmt.Fprintln(w)
+	w.Flush()
+}
+
+// printValuesJson fills a struct for json output
+func valuesToJSON(libName string, values []*compiler.Value) []ValueJSON {
+	val := []ValueJSON{}
+
+	for _, i := range values {
+		v := ValueJSON{}
+		v.Name = formatLabel(libName, i)
+		v.Type = common.FormatValue(i)
+		v.Description = common.ValueDocString(i)
+		val = append(val, v)
+	}
+
+	return val
+}
+
+func PrintDoc(ctx context.Context, packageName string, val *compiler.Value, format string) {
+	lg := log.Ctx(ctx)
+
+	fields, err := val.Fields(cue.Definitions(true))
+	if err != nil {
+		lg.Fatal().Err(err).Msg("cannot get fields")
+	}
+
+	packageJSON := &PackageJSON{}
+	// Package Name + Description
+	switch format {
+	case textFormat:
+		fmt.Printf("Package %s\n", packageName)
+		fmt.Printf("\n%s\n", common.ValueDocString(val))
+	case markdownFormat:
+		fmt.Printf("## Package %s\n", mdEscape(packageName))
+		comment := common.ValueDocString(val)
+		if comment == "-" {
+			fmt.Println()
+			break
+		}
+		fmt.Printf("\n%s\n\n", mdEscape(comment))
+	case jsonFormat:
+		packageJSON.Name = packageName
+		comment := common.ValueDocString(val)
+		if comment != "" {
+			packageJSON.Description = comment
+		}
+	}
+
+	// Package Fields
+	for _, field := range fields {
+		fieldJSON := FieldJSON{}
+
+		if !field.Selector.IsDefinition() {
+			// not a definition, skipping
+			continue
+		}
+
+		name := field.Label()
+		v := field.Value
+		if v.Cue().IncompleteKind() != cue.StructKind {
+			// not a struct, skipping
+			continue
+		}
+
+		// Field Name + Description
+		comment := common.ValueDocString(v)
+		switch format {
+		case textFormat:
+			fmt.Printf("\n%s\n\n%s%s\n", name, textPadding, comment)
+		case markdownFormat:
+			fmt.Printf("### %s\n\n", name)
+			if comment != "-" {
+				fmt.Printf("%s\n\n", mdEscape(comment))
+			}
+		case jsonFormat:
+			fieldJSON.Name = name
+			comment := common.ValueDocString(val)
+			if comment != "" {
+				fieldJSON.Description = comment
+			}
+		}
+
+		// Inputs
+		inp := environment.ScanInputs(ctx, v)
+		switch format {
+		case textFormat:
+			if len(inp) == 0 {
+				fmt.Printf("\n%sInputs: none\n", textPadding)
+				break
+			}
+			printValuesText(name, inp)
+		case markdownFormat:
+			fmt.Printf("#### %s Inputs\n\n", mdEscape(name))
+			if len(inp) == 0 {
+				fmt.Printf("_No input._\n\n")
+				break
+			}
+			printValuesMarkdown(name, inp)
+		case jsonFormat:
+			fieldJSON.Inputs = valuesToJSON(name, inp)
+		}
+
+		// Outputs
+		out := environment.ScanOutputs(ctx, v)
+		switch format {
+		case textFormat:
+			if len(out) == 0 {
+				fmt.Printf("\n%sOutputs: none\n", textPadding)
+				break
+			}
+			printValuesText(name, out)
+		case markdownFormat:
+			fmt.Printf("#### %s Outputs\n\n", mdEscape(name))
+			if len(out) == 0 {
+				fmt.Printf("_No output._\n\n")
+				break
+			}
+			printValuesMarkdown(name, out)
+		case jsonFormat:
+			fieldJSON.Outputs = valuesToJSON(name, out)
+			packageJSON.Fields = append(packageJSON.Fields, fieldJSON)
+		}
+	}
+
+	if format == jsonFormat {
+		data, err := json.MarshalIndent(packageJSON, "", "    ")
+		if err != nil {
+			lg.Fatal().Err(err).Msg("json marshal")
+		}
+		fmt.Printf("%s\n", data)
+	}
+}
diff --git a/cmd/dagger/cmd/input/list.go b/cmd/dagger/cmd/input/list.go
index a4c8130d..0d97d0f4 100644
--- a/cmd/dagger/cmd/input/list.go
+++ b/cmd/dagger/cmd/input/list.go
@@ -57,15 +57,6 @@ var listCmd = &cobra.Command{
 			for _, inp := range inputs {
 				isConcrete := (inp.IsConcreteR() == nil)
 				_, hasDefault := inp.Default()
-				// valStr := "-"
-				// if isConcrete {
-				// 	valStr, _ = inp.Cue().String()
-				// }
-				// if hasDefault {
-				// 	valStr = fmt.Sprintf("%s (default)", valStr)
-				// }
-
-				// valStr = strings.ReplaceAll(valStr, "\n", "\\n")
 
 				if !viper.GetBool("all") {
 					// skip input that is not overridable
diff --git a/cmd/dagger/cmd/root.go b/cmd/dagger/cmd/root.go
index 19ab0229..a4d0a061 100644
--- a/cmd/dagger/cmd/root.go
+++ b/cmd/dagger/cmd/root.go
@@ -46,6 +46,7 @@ func init() {
 		input.Cmd,
 		output.Cmd,
 		versionCmd,
+		docCmd,
 	)
 
 	if err := viper.BindPFlags(rootCmd.PersistentFlags()); err != nil {
diff --git a/compiler/value.go b/compiler/value.go
index ded6e810..167f3861 100644
--- a/compiler/value.go
+++ b/compiler/value.go
@@ -5,6 +5,7 @@ import (
 	"strconv"
 
 	"cuelang.org/go/cue"
+	"cuelang.org/go/cue/ast"
 	cueformat "cuelang.org/go/cue/format"
 )
 
@@ -75,8 +76,8 @@ func (f Field) Label() string {
 
 // Proxy function to the underlying cue.Value
 // Field ordering is guaranteed to be stable.
-func (v *Value) Fields() ([]Field, error) {
-	it, err := v.val.Fields()
+func (v *Value) Fields(opts ...cue.Option) ([]Field, error) {
+	it, err := v.val.Fields(opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -270,3 +271,11 @@ func (v *Value) Default() (*Value, bool) {
 	val, hasDef := v.val.Default()
 	return v.cc.Wrap(val), hasDef
 }
+
+func (v *Value) Doc() []*ast.CommentGroup {
+	return v.Cue().Doc()
+}
+
+func (v *Value) IncompleteKindString() string {
+	return v.Cue().IncompleteKind().String()
+}
diff --git a/environment/environment.go b/environment/environment.go
index a0aa24b7..260fd47d 100644
--- a/environment/environment.go
+++ b/environment/environment.go
@@ -320,7 +320,7 @@ func (e *Environment) ScanInputs(ctx context.Context, mergeUserInputs bool) ([]*
 		}
 	}
 
-	return scanInputs(ctx, src), nil
+	return ScanInputs(ctx, src), nil
 }
 
 func (e *Environment) ScanOutputs(ctx context.Context) ([]*compiler.Value, error) {
@@ -340,5 +340,5 @@ func (e *Environment) ScanOutputs(ctx context.Context) ([]*compiler.Value, error
 		}
 	}
 
-	return scanOutputs(ctx, src), nil
+	return ScanOutputs(ctx, src), nil
 }
diff --git a/environment/inputs_scan.go b/environment/inputs_scan.go
index 0939a9ac..7b3a3648 100644
--- a/environment/inputs_scan.go
+++ b/environment/inputs_scan.go
@@ -42,7 +42,7 @@ func isReference(val cue.Value) bool {
 	return isRef(val)
 }
 
-func scanInputs(ctx context.Context, value *compiler.Value) []*compiler.Value {
+func ScanInputs(ctx context.Context, value *compiler.Value) []*compiler.Value {
 	lg := log.Ctx(ctx)
 	inputs := []*compiler.Value{}
 
@@ -67,7 +67,7 @@ func scanInputs(ctx context.Context, value *compiler.Value) []*compiler.Value {
 	return inputs
 }
 
-func scanOutputs(ctx context.Context, value *compiler.Value) []*compiler.Value {
+func ScanOutputs(ctx context.Context, value *compiler.Value) []*compiler.Value {
 	lg := log.Ctx(ctx)
 	inputs := []*compiler.Value{}
 
diff --git a/go.mod b/go.mod
index 0ed3cba4..8352a529 100644
--- a/go.mod
+++ b/go.mod
@@ -30,6 +30,7 @@ require (
 	github.com/uber/jaeger-lib v2.4.1+incompatible // indirect
 	go.mozilla.org/sops/v3 v3.7.1
 	go.uber.org/atomic v1.7.0 // indirect
+	golang.org/x/crypto v0.0.0-20210220033148-5ea612d1eb83
 	golang.org/x/net v0.0.0-20210331212208-0fccb6fa2b5c // indirect
 	golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9
 	golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1