diff --git a/build.zig b/build.zig
index 73e957b..7b17d02 100644
--- a/build.zig
+++ b/build.zig
@@ -19,6 +19,9 @@ pub fn build(b: *std.Build) void {
 
     exe.pie = pie;
     exe.root_module.linkSystemLibrary("ncursesw", .{});
+    exe.root_module.linkSystemLibrary("zlib", .{});
+    exe.root_module.linkSystemLibrary("libzstd", .{});
+    exe.root_module.linkSystemLibrary("lz4", .{});
     // https://github.com/ziglang/zig/blob/b52be973dfb7d1408218b8e75800a2da3dc69108/build.zig#L551-L554
     if (target.result.isDarwin()) {
         // useful for package maintainers
diff --git a/src/bin_export.zig b/src/bin_export.zig
index 54904f3..de5f153 100644
--- a/src/bin_export.zig
+++ b/src/bin_export.zig
@@ -6,6 +6,11 @@ const main = @import("main.zig");
 const sink = @import("sink.zig");
 const util = @import("util.zig");
 const ui = @import("ui.zig");
+const c = @cImport({
+    @cInclude("zlib.h");
+    @cInclude("zstd.h");
+    @cInclude("lz4.h");
+});
 
 pub const global = struct {
     var fd: std.fs.File = undefined;
@@ -17,7 +22,7 @@ pub const global = struct {
     // var links: Map dev -> ino -> (last_offset, size, blocks, nlink)
 };
 
-const BLOCK_SIZE: usize = 64*1024;
+const BLOCK_SIZE: usize = 512*1024; // XXX: Current maximum for benchmarking, should just stick with a fixed block size.
 
 const ItemType = enum(i3) {
     dir = 0,
@@ -59,7 +64,7 @@ const ItemKey = enum(u5) {
 };
 
 // Pessimistic upper bound on the encoded size of an item, excluding the name field.
-// 2 bytes for map start/end, 10 per field (2 for the key, 9 for a full u64).
+// 2 bytes for map start/end, 11 per field (2 for the key, 9 for a full u64).
 const MAX_ITEM_LEN = 2 + 11 * @typeInfo(ItemKey).Enum.fields.len;
 
 const CborMajor = enum(u3) { pos, neg, bytes, text, array, map, tag, simple };
@@ -79,19 +84,48 @@ pub const Thread = struct {
     block_num: u32 = std.math.maxInt(u32),
     itemref: u64 = 0, // ref of item currently being written
 
-    // Temporary buffer for headers and compression
+    // Temporary buffer for headers and compression.
+    // TODO: check with compressBound()/ZSTD_compressBound()
     tmp: [BLOCK_SIZE+128]u8 = undefined,
 
+    fn compressNone(in: []const u8, out: []u8) usize {
+        @memcpy(out[0..in.len], in);
+        return in.len;
+    }
+
+    fn compressZlib(in: []const u8, out: []u8) usize {
+        var outlen: c.uLongf = out.len;
+        const r = c.compress2(out.ptr, &outlen, in.ptr, in.len, main.config.complevel);
+        std.debug.assert(r == c.Z_OK);
+        return outlen;
+    }
+
+    fn compressZstd(in: []const u8, out: []u8) usize {
+        const r = c.ZSTD_compress(out.ptr, out.len, in.ptr, in.len, main.config.complevel);
+        std.debug.assert(c.ZSTD_isError(r) == 0);
+        return r;
+    }
+
+    fn compressLZ4(in: []const u8, out: []u8) usize {
+        const r = c.LZ4_compress_default(in.ptr, out.ptr, @intCast(in.len), @intCast(out.len));
+        std.debug.assert(r > 0);
+        return @intCast(r);
+    }
+
     fn createBlock(t: *Thread) []const u8 {
         if (t.block_num == std.math.maxInt(u32) or t.off <= 1) return "";
 
-        // TODO: Compression
-        const blocklen: u32 = @intCast(t.off + 16);
+        const bodylen = switch (main.config.compression) {
+            .none => compressNone(t.buf[0..t.off], t.tmp[12..]),
+            .zlib => compressZlib(t.buf[0..t.off], t.tmp[12..]),
+            .zstd => compressZstd(t.buf[0..t.off], t.tmp[12..]),
+            .lz4 => compressLZ4(t.buf[0..t.off], t.tmp[12..]),
+        };
+        const blocklen: u32 = @intCast(bodylen + 16);
         t.tmp[0..4].* = blockHeader(1, blocklen);
         t.tmp[4..8].* = bigu32(t.block_num);
         t.tmp[8..12].* = bigu32(@intCast(t.off));
-        @memcpy(t.tmp[12..][0..t.off], t.buf[0..t.off]);
-        t.tmp[12+t.off..][0..4].* = blockHeader(1, blocklen);
+        t.tmp[12+bodylen..][0..4].* = blockHeader(1, blocklen);
         return t.tmp[0..blocklen];
     }
 
@@ -164,7 +198,7 @@ pub const Thread = struct {
     // Reserve space for a new item, write out the type, prev and name fields and return the itemref.
     fn itemStart(t: *Thread, itype: ItemType, prev_item: u64, name: []const u8) u64 {
         const min_len = name.len + MAX_ITEM_LEN;
-        if (t.off + min_len > t.buf.len) t.flush(min_len);
+        if (t.off + min_len > main.config.blocksize) t.flush(min_len);
 
         t.itemref = (@as(u64, t.block_num) << 24) | t.off;
         t.cborIndef(.map);
diff --git a/src/main.zig b/src/main.zig
index 73fdce0..0fc9f7c 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -70,6 +70,9 @@ pub const config = struct {
     pub var exclude_kernfs: bool = false;
     pub var exclude_patterns: std.ArrayList([:0]const u8) = std.ArrayList([:0]const u8).init(allocator);
     pub var threads: usize = 1;
+    pub var compression: enum { none, zlib, zstd, lz4 } = .none;
+    pub var complevel: u8 = 5;
+    pub var blocksize: usize = 64*1024;
 
     pub var update_delay: u64 = 100*std.time.ns_per_ms;
     pub var scan_ui: ?enum { none, line, full } = null;
@@ -502,7 +505,17 @@ pub fn main() void {
             else if (opt.is("-f")) import_file = allocator.dupeZ(u8, args.arg()) catch unreachable
             else if (opt.is("--ignore-config")) {}
             else if (opt.is("--quit-after-scan")) quit_after_scan = true // undocumented feature to help with benchmarking scan/import
-            else if (argConfig(&args, opt)) {}
+            else if (opt.is("--binfmt")) { // Experimental, for benchmarking
+                const a = args.arg();
+                config.compression = switch (a[0]) {
+                    'z' => .zlib,
+                    's','S' => .zstd,
+                    'l' => .lz4,
+                    else => .none,
+                };
+                config.complevel = (a[1] - '0') + (if (a[0] == 'S') @as(u8, 10) else 0);
+                config.blocksize = @as(usize, 8*1024) << @intCast(a[2] - '0'); // 0 = 8k, 1 16k, 2 32k, 3 64k, 4 128k, 5 256k, 6 512k
+            } else if (argConfig(&args, opt)) {}
             else ui.die("Unrecognized option '{s}'.\n", .{opt.val});
         }
     }