Go build obfuscator.

Daniel Martí a186419d3d avoid rebuilding garble in the main benchmark 1 week ago
.github 1f39d0af72 update gotip and adapt to upstream changes 2 weeks ago
internal cf49f7f3b1 use the host's GOEXE when building the linker 2 weeks ago
scripts 6c4274c326 scripts: remove TODO about building third party programs 4 weeks ago
testdata 9d04637009 ensure the alignment of sync/atomic types works 2 weeks ago
.gitattributes ab560ff007 start testing on GitHub Actions 3 years ago
.gitignore 12bc0349e6 make bincmp keep binaries around when it fails 4 months ago
AUTHORS 22e3d30216 support code taking the address of a []byte literal (#530) 10 months ago
CHANGELOG.md 89facf1648 CHANGELOG: prepare for v0.9.3 1 month ago
CONTRIBUTING.md 8e7765ee6f CONTRIBUTING: introduce -toolexec and add more dev tips 1 year ago
LICENSE 805c895d59 set up an AUTHORS file to attribute copyright 2 years ago
README.md b322876efe drop support for Go 1.19 1 month ago
bench_test.go a186419d3d avoid rebuilding garble in the main benchmark 6 days ago
cmdgo_quoted.go 598d5182fb update x/tools version used in go:generate 2 months ago
go.mod e37f39054d update testscript to support code coverage with Go 1.20 1 month ago
go.sum e37f39054d update testscript to support code coverage with Go 1.20 1 month ago
go_std_tables.go 9598e439ed CI: test against a newer Go tip 4 weeks ago
hash.go 86b7e334ba implement funcInfo.entryoff encryption 1 month ago
main.go 9d04637009 ensure the alignment of sync/atomic types works 2 weeks ago
main_test.go a186419d3d avoid rebuilding garble in the main benchmark 6 days ago
position.go 60dbece24f work around another go/printer bug to fix andybalholm/brotli 6 months ago
reverse.go ac0945eaa5 work around cmd/go issue relating to CompiledGoFiles 6 months ago
runtime_patch.go 1f39d0af72 update gotip and adapt to upstream changes 2 weeks ago
shared.go 30927da637 avoid panic when a package's imports cannot be loaded 2 weeks ago



go install mvdan.cc/garble@latest

Obfuscate Go code by wrapping the Go toolchain. Requires Go 1.20 or later.

garble build [build flags] [packages]

The tool also supports garble test to run tests with obfuscated code, and garble reverse to de-obfuscate text such as stack traces. See garble -h for up to date usage information.


Produce a binary that works as well as a regular build, but that has as little information about the original source code as possible.

The tool is designed to be:

  • Coupled with cmd/go, to support modules and build caching
  • Deterministic and reproducible, given the same initial source code
  • Reversible given the original source, to de-obfuscate panic stack traces


The tool wraps calls to the Go compiler and linker to transform the Go build, in order to:

  • Replace as many useful identifiers as possible with short base64 hashes
  • Replace package paths with short base64 hashes
  • Replace filenames and position information with short base64 hashes
  • Remove all build and module information
  • Strip debugging information and symbol tables via -ldflags="-w -s"
  • Obfuscate literals, if the -literals flag is given
  • Remove extra information, if the -tiny flag is given

By default, the tool obfuscates all the packages being built. You can manually specify which packages to obfuscate via GOGARBLE, a comma-separated list of glob patterns matching package path prefixes. This format is borrowed from GOPRIVATE; see go help private.

Note that commands like garble build will use the go version found in your $PATH. To use different versions of Go, you can install them and set up $PATH with them. For example, for Go 1.17.1:

$ go install golang.org/dl/go1.17.1@latest
$ go1.17.1 download
$ PATH=$(go1.17.1 env GOROOT)/bin:${PATH} garble build

Literal obfuscation

Using the -literals flag causes literal expressions such as strings to be replaced with more complex expressions, resolving to the same value at run-time. String literals injected via -ldflags=-X are also replaced by this flag. This feature is opt-in, as it can cause slow-downs depending on the input code.

Literals used in constant expressions cannot be obfuscated, since they are resolved at compile time. This includes any expressions part of a const declaration, for example.

Tiny mode

With the -tiny flag, even more information is stripped from the Go binary. Position information is removed entirely, rather than being obfuscated. Runtime code which prints panics, fatal errors, and trace/debug info is removed. Many symbol names are also omitted from binary sections at link time. All in all, this can make binaries about 15% smaller.

With this flag, no panics or fatal runtime errors will ever be printed, but they can still be handled internally with recover as normal. In addition, the GODEBUG environmental variable will be ignored.

Note that this flag can make debugging crashes harder, as a panic will simply exit the entire program without printing a stack trace, and source code positions and many names are removed. Similarly, garble reverse is generally not useful in this mode.


garble build should take about twice as long as go build, as it needs to complete two builds. The original build, to be able to load and type-check the input code, and then the obfuscated build.

Garble obfuscates one package at a time, mirroring how Go compiles one package at a time. This allows Garble to fully support Go's build cache; incremental garble build calls should only re-build and re-obfuscate modified code.

Note that the first call to garble build may be comparatively slow, as it has to obfuscate each package for the first time. This is akin to clearing GOCACHE with go clean -cache and running a go build from scratch.

Determinism and seeds

Just like Go, garble builds are deterministic and reproducible in nature. This has significant benefits, such as caching builds and being able to use garble reverse to de-obfuscate stack traces.

By default, garble will obfuscate each package in a unique way, which will change if its build input changes: the version of garble, the version of Go, the package's source code, or any build parameter such as GOOS or -tags. This is a reasonable default since guessing those inputs is very hard.

You can use the -seed flag to provide your own obfuscation randomness seed. Reusing the same seed can help produce the same code obfuscation, which can help when debugging or reproducing problems. Regularly rotating the seed can also help against reverse-engineering in the long run, as otherwise one can look at changes in how Go's standard library is obfuscated to guess when the Go or garble versions were changed across a series of builds.

To always use a different seed for each build, use -seed=random. Note that extra care should be taken when using custom seeds: if a -seed value used in a build is lost, garble reverse will not work.


Most of these can improve with time and effort. The purpose of this section is to document the current shortcomings of this tool.

  • Exported methods are never obfuscated at the moment, since they could be required by interfaces. This area is a work in progress; see #3.

  • Garble aims to automatically detect which Go types are used with reflection, as obfuscating those types might break your program. Note that Garble obfuscates one package at a time, so if your reflection code inspects a type from an imported package, and your program broke, you may need to add a "hint" in the imported package:

    type Message struct {
       Command string
       Args    string
    // Never obfuscate the Message type.
    var _ = reflect.TypeOf(Message{})
  • Go plugins are not currently supported; see #87.

  • Garble requires git to patch the linker. That can be avoided once go-gitdiff supports non-strict patches.


We welcome new contributors. If you would like to contribute, see CONTRIBUTING.md as a starting point.