diff --git a/Makefile b/Makefile
index 8ae28c4d..2ffe89f2 100644
--- a/Makefile
+++ b/Makefile
@@ -134,7 +134,7 @@ objects = ctree.o disk-io.o kernel-lib/radix-tree.o extent-tree.o print-tree.o \
 	  common/task-utils.o \
 	  inode.o file.o find-root.o free-space-tree.o common/help.o send-dump.o \
 	  common/fsfeatures.o kernel-lib/tables.o kernel-lib/raid56.o transaction.o \
-	  delayed-ref.o
+	  delayed-ref.o common/format-output.o
 cmds_objects = cmds/subvolume.o cmds/filesystem.o cmds/device.o cmds/scrub.o \
 	       cmds/inspect.o cmds/balance.o cmds/send.o cmds/receive.o \
 	       cmds/quota.o cmds/qgroup.o cmds/replace.o check/main.o \
diff --git a/common/format-output.c b/common/format-output.c
new file mode 100644
index 00000000..c5f1b51f
--- /dev/null
+++ b/common/format-output.c
@@ -0,0 +1,314 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include "kerncompat.h"
+#include <stdio.h>
+#include <uuid/uuid.h>
+#include "common-defs.h"
+#include "common/format-output.h"
+#include "common/utils.h"
+#include "cmds/commands.h"
+
+static void print_uuid(const u8 *uuid)
+{
+	char uuidparse[BTRFS_UUID_UNPARSED_SIZE];
+
+	if (uuid_is_null(uuid)) {
+		putchar('-');
+	} else {
+		uuid_unparse(uuid, uuidparse);
+		printf("%s", uuidparse);
+	}
+}
+
+static void fmt_indent1(int indent)
+{
+	while (indent--)
+		putchar(' ');
+}
+
+static void fmt_indent2(int indent)
+{
+	while (indent--) {
+		putchar(' ');
+		putchar(' ');
+	}
+}
+
+static void fmt_error(struct format_ctx *fctx)
+{
+	printf("INTERNAL ERROR: formatting json: depth=%d\n", fctx->depth);
+	exit(1);
+}
+
+static void fmt_inc_depth(struct format_ctx *fctx)
+{
+	if (fctx->depth >= JSON_NESTING_LIMIT - 1) {
+		printf("INTERNAL ERROR: nesting too deep, limit %d\n",
+				JSON_NESTING_LIMIT);
+		exit(1);
+	}
+	fctx->depth++;
+}
+
+static void fmt_dec_depth(struct format_ctx *fctx)
+{
+	if (fctx->depth < 1) {
+		printf("INTERNAL ERROR: nesting below first level\n");
+		exit(1);
+	}
+	fctx->depth--;
+}
+
+static void fmt_separator(struct format_ctx *fctx)
+{
+	if (bconf.output_format == CMD_FORMAT_JSON) {
+		/* Check current depth */
+		if (fctx->memb[fctx->depth] == 0) {
+			/* First member, only indent */
+			putchar('\n');
+			fmt_indent2(fctx->depth);
+			fctx->memb[fctx->depth] = 1;
+		} else if (fctx->memb[fctx->depth] == 1) {
+			/* Something has been printed already */
+			printf(",\n");
+			fmt_indent2(fctx->depth);
+			fctx->memb[fctx->depth] = 2;
+		} else {
+			/* N-th member */
+			printf(",\n");
+			fmt_indent2(fctx->depth);
+		}
+	}
+}
+
+void fmt_start(struct format_ctx *fctx, const struct rowspec *spec, int width,
+		int indent)
+{
+	fctx->width = width;
+	fctx->indent = indent;
+	fctx->rowspec = spec;
+	fctx->depth = 1;
+
+	if (bconf.output_format & CMD_FORMAT_JSON) {
+		putchar('{');
+		/* The top level is a map and is the first one */
+		fctx->jtype[fctx->depth] = JSON_TYPE_MAP;
+		fctx->memb[fctx->depth] = 0;
+		fmt_print_start_group(fctx, "__header", JSON_TYPE_MAP);
+		fmt_separator(fctx);
+		printf("\"version\": \"1\"");
+		fctx->memb[fctx->depth] = 1;
+		fmt_print_end_group(fctx, "__header");
+	}
+}
+
+void fmt_end(struct format_ctx *fctx)
+{
+	if (fctx->depth != 1)
+		fprintf(stderr, "WARNING: wrong nesting\n");
+
+	/* Close, no continuation to print */
+
+	if (bconf.output_format & CMD_FORMAT_TEXT)
+		putchar('\n');
+	else if (bconf.output_format & CMD_FORMAT_JSON) {
+		fmt_dec_depth(fctx);
+		fmt_separator(fctx);
+		printf("}\n");
+	}
+}
+
+void fmt_start_list_value(struct format_ctx *fctx)
+{
+	if (bconf.output_format == CMD_FORMAT_TEXT) {
+		fmt_indent1(fctx->indent);
+	} else if (bconf.output_format == CMD_FORMAT_JSON) {
+		fmt_separator(fctx);
+		fmt_indent2(fctx->depth);
+		putchar('"');
+	}
+}
+
+void fmt_end_list_value(struct format_ctx *fctx)
+{
+	if (bconf.output_format == CMD_FORMAT_TEXT)
+		putchar('\n');
+	else if (bconf.output_format == CMD_FORMAT_JSON)
+		putchar('"');
+}
+
+void fmt_start_value(struct format_ctx *fctx, const struct rowspec *row)
+{
+	if (bconf.output_format == CMD_FORMAT_TEXT) {
+		if (strcmp(row->fmt, "list") == 0)
+			putchar('\n');
+		else if (strcmp(row->fmt, "map") == 0)
+			putchar('\n');
+	} else if (bconf.output_format == CMD_FORMAT_JSON) {
+		if (strcmp(row->fmt, "list") == 0) {
+		} else if (strcmp(row->fmt, "map") == 0) {
+		} else {
+			putchar('"');
+		}
+	}
+}
+
+void fmt_end_value(struct format_ctx *fctx, const struct rowspec *row)
+{
+	if (bconf.output_format == CMD_FORMAT_JSON) {
+		if (strcmp(row->fmt, "list") == 0) {
+		} else if (strcmp(row->fmt, "map") == 0) {
+		} else {
+			putchar('"');
+		}
+	}
+}
+
+void fmt_print_start_group(struct format_ctx *fctx, const char *name,
+		enum json_type jtype)
+{
+	if (bconf.output_format == CMD_FORMAT_JSON) {
+		fmt_separator(fctx);
+		fmt_inc_depth(fctx);
+		fctx->jtype[fctx->depth] = jtype;
+		fctx->memb[fctx->depth] = 0;
+		if (jtype == JSON_TYPE_MAP)
+			printf("\"%s\": {", name);
+		else if (jtype == JSON_TYPE_ARRAY)
+			printf("\"%s\": [", name);
+		else
+			fmt_error(fctx);
+	}
+}
+
+void fmt_print_end_group(struct format_ctx *fctx, const char *name)
+{
+	if (bconf.output_format == CMD_FORMAT_JSON) {
+		/* Whatever was on previous line won't continue with "," */
+		const enum json_type jtype = fctx->jtype[fctx->depth];
+
+		fmt_dec_depth(fctx);
+		putchar('\n');
+		fmt_indent2(fctx->depth);
+		if (jtype == JSON_TYPE_MAP)
+			putchar('}');
+		else if (jtype == JSON_TYPE_ARRAY)
+			putchar(']');
+		else
+			fmt_error(fctx);
+	}
+}
+
+/* Use rowspec to print according to currently set output format */
+void fmt_print(struct format_ctx *fctx, const char* key, ...)
+{
+	va_list args;
+	const struct rowspec *row;
+	bool found = false;
+
+	va_start(args, key);
+	row = &fctx->rowspec[0];
+
+	while (row->key) {
+		if (strcmp(key, row->key) == 0) {
+			found = true;
+			break;
+		}
+		row++;
+	}
+	if (!found) {
+		printf("INTERNAL ERROR: unknown key: %s\n", key);
+		exit(1);
+	}
+
+	if (bconf.output_format == CMD_FORMAT_TEXT) {
+		const bool print_colon = row->out_text[0];
+		int len;
+
+		putchar('\n');
+		fmt_indent1(fctx->indent);
+		len = strlen(row->out_text);
+
+		printf("%s", row->out_text);
+		if (print_colon) {
+			putchar(':');
+			len++;
+		}
+		fmt_indent1(fctx->width - len);
+	} else if (bconf.output_format == CMD_FORMAT_JSON) {
+		if (strcmp(row->fmt, "list") == 0) {
+			fmt_print_start_group(fctx, row->out_json,
+					JSON_TYPE_ARRAY);
+		} else if (strcmp(row->fmt, "map") == 0) {
+			fmt_print_start_group(fctx, row->out_json,
+					JSON_TYPE_MAP);
+		} else {
+			/* Simple key/values */
+			fmt_separator(fctx);
+			printf("\"%s\": ", row->out_json);
+		}
+	}
+
+	fmt_start_value(fctx, row);
+
+	if (row->fmt[0] == '%') {
+		vprintf(row->fmt, args);
+	} else if (strcmp(row->fmt, "uuid") == 0) {
+		const u8 *uuid = va_arg(args, const u8*);
+
+		print_uuid(uuid);
+	} else if (strcmp(row->fmt, "time-long") == 0) {
+		const time_t ts = va_arg(args, time_t);
+
+		if (ts) {
+			char tstr[256];
+			struct tm tm;
+
+			localtime_r(&ts, &tm);
+			strftime(tstr, 256, "%Y-%m-%d %X %z", &tm);
+			printf(tstr);
+		} else {
+			putchar('-');
+		}
+	} else if (strcmp(row->fmt, "list") == 0) {
+	} else if (strcmp(row->fmt, "map") == 0) {
+	} else if (strcmp(row->fmt, "qgroupid") == 0) {
+		const u64 level = va_arg(args, u64);
+		const u64 id = va_arg(args, u64);
+
+		printf("%llu/%llu", level, id);
+	} else if (strcmp(row->fmt, "size-or-none") == 0) {
+		const u64 size = va_arg(args, u64);
+		const unsigned int unit_mode = va_arg(args, unsigned int);
+
+		if (size)
+			printf("%s", pretty_size_mode(size, unit_mode));
+		else
+			putchar('-');
+	} else if (strcmp(row->fmt, "size") == 0) {
+		const u64 size = va_arg(args, u64);
+		const unsigned int unit_mode = va_arg(args, unsigned int);
+
+		printf("%s", pretty_size_mode(size, unit_mode));
+	} else {
+		printf("INTERNAL ERROR: unknown format %s\n", row->fmt);
+	}
+
+	fmt_end_value(fctx, row);
+	/* No newline here, the line is closed by next value or group end */
+	va_end(args);
+}
diff --git a/common/format-output.h b/common/format-output.h
new file mode 100644
index 00000000..b73f53ba
--- /dev/null
+++ b/common/format-output.h
@@ -0,0 +1,90 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#ifndef __BTRFS_FORMAT_OUTPUT_H__
+#define __BTRFS_FORMAT_OUTPUT_H__
+
+struct rowspec {
+	/* Identifier for the row */
+	const char *key;
+	/*
+	 * Format to print:
+	 * - starting with %: must be a valid printf spec
+	 *   (values: va_args)
+	 * - uuid: format UUID as text
+	 *   (value: u8 *uuid)
+	 * - list: print list opening bracket [
+	 *   (values printed separately)
+	 * - map:  start a new group, opens {
+	 *   (values printed separately)
+	 * - size: pretty print size according to
+	 *   (values: u64 size, u32 unit_type)
+	 * - size-or-none: pretty print non-zero values, "-" otherwise
+	 *   (values: same as "size")
+	 * - qgroupid: print qgroup from separate level and id
+	 *   (values: u64 level, u64 id)
+	 */
+	const char *fmt;
+	/* String to print in format:text */
+	const char *out_text;
+	/* String to print in format:json, is quoted */
+	const char *out_json;
+};
+
+#define	ROWSPEC_END	{ .key = NULL },
+#define JSON_NESTING_LIMIT	16
+
+/*
+ * Nested types
+ */
+enum json_type {
+	JSON_TYPE_INVALID,
+	JSON_TYPE_MAP,
+	JSON_TYPE_ARRAY,
+};
+
+struct format_ctx {
+	/* Preferred width of the first column with key (format: text) */
+	int width;
+	/* Initial indentation before the first column (format: text) */
+	int indent;
+	/* Nesting of groups like lists or maps (format: json) */
+	int depth;
+
+	/* Array of named output fileds as defined by the command */
+	const struct rowspec *rowspec;
+
+	char jtype[JSON_NESTING_LIMIT];
+	enum json_type memb[JSON_NESTING_LIMIT];
+};
+
+void fmt_start(struct format_ctx *fctx, const struct rowspec *spec, int width,
+		int indent);
+void fmt_end(struct format_ctx *fctx);
+
+void fmt_print(struct format_ctx *fctx, const char* key, ...);
+
+void fmt_start_list_value(struct format_ctx *fctx);
+void fmt_end_list_value(struct format_ctx *fctx);
+
+void fmt_start_value(struct format_ctx *fctx, const struct rowspec *row);
+void fmt_end_value(struct format_ctx *fctx, const struct rowspec *row);
+
+void fmt_print_start_group(struct format_ctx *fctx, const char *name,
+		enum json_type jtype);
+void fmt_print_end_group(struct format_ctx *fctx, const char *name);
+
+#endif