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Skycoin is a next-generation cryptocurrency.

Skycoin was written from scratch and designed over four years to realize the ideal of Bitcoin and represents the apex of cryptocurrency design. Skycoin is not designed to add features to Bitcoin, but rather improves Bitcoin by increasing simplicity, security and stripping out everything non-essential.

Some people have hyped the Skycoin Project as leading into "Bitcoin 3.0". The coin itself is not "Bitcoin 3.0", but is rather "Bitcoin 1.0". Bitcoin is a prototype crypto-coin. Skycoin was designed to be what Bitcoin would look like if it were built from scratch, to remedy the rough edges in the Bitcoin design.

  • no duplicate coin-base outputs
  • enforced checks for hash collisions
  • simple deterministic wallets
  • no transaction malleability
  • no signature malleability
  • removal of the scripting language
  • CoinJoin and normal transactions are indistinguishable
  • elimination of edge-cases that prevent independent node implementations
  • <=10 second transaction times
  • elimination of the need for mining to achieve blockchain consensus


Table of Contents



Skycoin supports go1.10+.

Go 1.10+ Installation and Setup

Golang 1.10+ Installation/Setup

Go get skycoin

$ go get

This will download to $GOPATH/src/

You can also clone the repo directly with git clone, but it must be cloned to this path: $GOPATH/src/

Run Skycoin from the command line

$ cd $GOPATH/src/
$ make run-client

Show Skycoin node options

$ cd $GOPATH/src/
$ make run-help

Run Skycoin with options


$ cd $GOPATH/src/
$ make ARGS="--launch-browser=false -data-dir=/custom/path" run

Docker image

This is the quickest way to start using Skycoin using Docker.

$ docker volume create skycoin-data
$ docker volume create skycoin-wallet
$ docker run -ti --rm \
    -v skycoin-data:/data/.skycoin \
    -v skycoin-wallet:/wallet \
    -p 6000:6000 \
    -p 6420:6420 \

This image has a skycoin user for the skycoin daemon to run, with UID and GID 10000. When you mount the volumes, the container will change their owner, so you must be aware that if you are mounting an existing host folder any content you have there will be own by 10000.

The container will run with some default options, but you can change them by just appending flags at the end of the docker run command. The following example will show you the available options.

$ docker run --rm skycoin/skycoin -help

Access the dashboard: http://localhost:6420.

Access the API: http://localhost:6420/version.

Building your own images

Building your own images.

Development image

The skycoin/skycoindev-cli docker image is provided in order to make easy to start developing Skycoin. It comes with the compiler, linters, debugger and the vim editor among other tools.

The skycoin/skycoindev-dind docker image comes with docker installed and all tools available on skycoin/skycoindev-cli:develop docker image.

Also, the skycoin/skycoindev-vscode docker image is provided to facilitate the setup of the development process with Visual Studio Code and useful tools included in skycoin/skycoindev-cli.

API Documentation



Skycoin command line interface

CLI command API.

Integrating Skycoin with your application

Skycoin Integration Documentation

Contributing a node to the network

Add your node's ip:port to the peers.txt file. This file will be periodically uploaded to and used to seed client with peers.

Note: Do not add Skywire nodes to peers.txt. Only add Skycoin nodes with high uptime and a static IP address (such as a Skycoin node hosted on a VPS).

Creating a new coin

See the newcoin tool README

Running with a custom coin hour burn factor

The coin hour burn factor is the denominator in the ratio of coinhours that must be burned by a transaction. For example, a burn factor of 2 means 1/2 of hours must be burned. A burn factor of 10 means 1/10 of coin hours must be burned.

The coin hour burn factor can be configured with a USER_BURN_FACTOR envvar. It cannot be configured through the command line.


This burn factor applies to user-created transactions.

To control the burn factor in other scenarios, use -burn-factor-unconfirmed and -burn-factor-create-block.

Running with a custom max transaction size


This maximum transaction size applies to user-created transactions.

To control the transaction size in other scenarios, use -max-txn-size-unconfirmed and -max-txn-size-create-block.

To control the max block size, use -max-block-size.

Transaction and block size are measured in bytes.

Running with a custom max decimal places


This maximum transaction size applies to user-created transactions.

To control the maximum decimals in other scenarios, use -max-decimals-unconfirmed and -max-decimals-create-block.

URI Specification

Skycoin URIs obey the same rules as specified in Bitcoin's BIP21. They use the same fields, except with the addition of an optional hours parameter, specifying the coin hours.

Example Skycoin URIs:

  • skycoin:2hYbwYudg34AjkJJCRVRcMeqSWHUixjkfwY
  • skycoin:2hYbwYudg34AjkJJCRVRcMeqSWHUixjkfwY?amount=123.456&hours=70
  • skycoin:2hYbwYudg34AjkJJCRVRcMeqSWHUixjkfwY?amount=123.456&hours=70&label=friend&message=Birthday%20Gift

Additonally, if no skycoin: prefix is present when parsing, the string may be treated as an address:

  • 2hYbwYudg34AjkJJCRVRcMeqSWHUixjkfwY

However, do not use this URI in QR codes displayed to the user, because the address can't be disambiguated from other Skyfiber coins.

Wire protocol user agent

Wire protocol user agent description


We have two branches: master and develop.

develop is the default branch and will have the latest code.

master will always be equal to the current stable release on the website, and should correspond with the latest release tag.


  • api - REST API interface
  • cipher - cryptographic library (key generation, addresses, hashes)
  • cipher/base58 - Base58 encoding
  • cipher/encoder - reflect-based deterministic runtime binary encoder
  • cipher/encrypt - at-rest data encryption (chacha20poly1305+scrypt)
  • cipher/go-bip39 - BIP-39 seed generation
  • cli - CLI library
  • coin - blockchain data structures (blocks, transactions, unspent outputs)
  • daemon - top-level application manager, combining all components (networking, database, wallets)
  • daemon/gnet - networking library
  • daemon/pex - peer management
  • params - configurable transaction verification parameters
  • readable - JSON-encodable representations of internal structures
  • skycoin - core application initialization and configuration
  • testutil - testing utility methods
  • transaction - methods for creating transactions
  • util - miscellaneous utilities
  • visor - top-level blockchain database layer
  • visor/blockdb - low-level blockchain database layer
  • visor/historydb - low-level blockchain database layer for historical blockchain metadata
  • wallet - wallet file management

Client libraries

Skycoin implements client libraries which export core functionality for usage from other programming languages.

Running Tests

$ make test

Running Integration Tests

There are integration tests for the CLI and HTTP API interfaces. They have two run modes, "stable" and "live".

The stable integration tests will use a skycoin daemon whose blockchain is synced to a specific point and has networking disabled so that the internal state does not change.

The live integration tests should be run against a synced or syncing node with networking enabled.

Stable Integration Tests

$ make integration-test-stable


$ ./ci-scripts/ -v -w

The -w option, run wallet integrations tests.

The -v option, show verbose logs.

Live Integration Tests

The live integration tests run against a live runnning skycoin node, so before running the test, we need to start a skycoin node:

$ ./

After the skycoin node is up, run the following command to start the live tests:

$ make integration-test-live

The above command will run all tests except the wallet-related tests. To run wallet tests, we need to manually specify a wallet file, and it must have at least 2 coins and 256 coinhours, it also must have been loaded by the node.

We can specify the wallet by setting two environment variables: WALLET_DIR and WALLET_NAME. The WALLET_DIR represents the absolute path of the wallet directory, and WALLET_NAME represents the wallet file name.

Note: WALLET_DIR is only used by the CLI integration tests. The GUI integration tests use the node's configured wallet directory, which can be controlled with -wallet-dir when running the node.

If the wallet is encrypted, also set WALLET_PASSWORD.

$ export WALLET_DIR="$HOME/.skycoin/wallets"
$ export WALLET_NAME="$valid_wallet_filename"
$ export WALLET_PASSWORD="$wallet_password"
$ ./ -launch-browser=false -enable-all-api-sets

Then run the tests with the following command:

$ make integration-test-live-wallet

There are two other live integration test modes for CSRF disabled and networking disabled.

To run the CSRF disabled tests:

$ ./ -disable-csrf
$ make integration-test-live-disable-csrf

To run the networking disabled tests, which requires a live wallet:

$ ./ -disable-networking -launch-browser=false
$ export WALLET_DIR="$HOME/.skycoin/wallets"
$ export WALLET_NAME="$valid_wallet_filename"
$ export WALLET_PASSWORD="$wallet_password"
$ make integration-test-live-disable-networking

Debugging Integration Tests

Run specific test case:

It's annoying and a waste of time to run all tests to see if the test we real care is working correctly. There's an option: -r, which can be used to run specific test case. For example: if we only want to test TestStableAddressBalance and see the result, we can run:

$ ./ci-scripts/ -v -r TestStableAddressBalance

Update golden files in integration testdata

Golden files are expected data responses from the CLI or HTTP API saved to disk. When the tests are run, their output is compared to the golden files.

To update golden files, use the provided make command:

$ make update-golden-files

We can also update a specific test case's golden file with the -r option. For example:

$ ./ci-scripts/ -v -u -r TestStableAddressBalance

Test coverage

Coverage is automatically generated for make test and integration tests run against a stable node. This includes integration test coverage. The coverage output files are placed in coverage/.

To merge coverage from all tests into a single HTML file for viewing:

$ make check
$ make merge-coverage

Then open coverage/all-coverage.html in the browser.

Test coverage for the live node

Some tests can only be run with a live node, for example wallet spending tests. To generate coverage for this, build and run the skycoin node in test mode before running the live integration tests.

In one shell:

$ make run-integration-test-live-cover

In another shell:

$ make integration-test-live

After the tests have run, CTRL-C to exit the process from the first shell. A coverage file will be generated at coverage/skycoin-live.coverage.out.

Merge the coverage with make merge-coverage then open the coverage/all-coverage.html file to view it, or generate the HTML coverage in isolation with go tool cover -html


All .go source files should be formatted goimports. You can do this with:

$ make format

Code Linting

Install prerequisites:

$ make install-linters

Run linters:

$ make lint


A full CPU profile of the program from start to finish can be obtained by running the node with the -profile-cpu flag. Once the node terminates, a profile file is written to -profile-cpu-file (defaults to This profile can be analyzed with

$ go tool pprof

The HTTP interface for obtaining more profiling data or obtaining data while running can be enabled with -http-prof. The HTTP profiling interface can be controlled with -http-prof-host and listens on localhost:6060 by default.

See for guidance on using the HTTP profiler.

Some useful examples include:

$ go tool pprof http://localhost:6060/debug/pprof/profile?seconds=10
$ go tool pprof http://localhost:6060/debug/pprof/heap

A web page interface is provided by http/pprof at http://localhost:6060/debug/pprof/.


Fuzz tests are run with go-fuzz. Follow the instructions on the go-fuzz page to install it.

Fuzz tests are written for the following packages:


To fuzz the cipher/base58 package,

$ make fuzz-base58


To fuzz the cipher/encoder package,

$ make fuzz-encoder



Dependencies must not require cgo. This means dependencies cannot be wrappers around C libraries. Requiring cgo breaks cross compilation and interferes with repeatable (deterministic) builds.

Critical cryptographic dependencies used by code in package cipher are archived inside the cipher folder, rather than in the vendor folder. This prevents a user of the cipher package from accidentally using a different version of the cipher dependencies than were developed, which could have catastrophic but hidden problems.


Dependencies are managed with dep.

To install dep for development:

$ go get -u

dep vendors all dependencies into the repo.

If you change the dependencies, you should update them as needed with dep ensure.

Use dep help for instructions on vendoring a specific version of a dependency, or updating them.

When updating or initializing, dep will find the latest version of a dependency that will compile.


Initialize all dependencies:

$ dep init

Update all dependencies:

$ dep ensure -update -v

Add a single dependency (latest version):

$ dep ensure

Add a single dependency (more specific version), or downgrade an existing dependency:

$ dep ensure[email protected]

Configuration Modes

There are 4 configuration modes in which you can run a skycoin node:

  • Development Desktop Daemon
  • Server Daemon
  • Electron Desktop Client
  • Standalone Desktop Client

Development Desktop Client Mode

This mode is configured via

$ ./

Server Daemon Mode

The default settings for a skycoin node are chosen for Server Daemon, which is typically run from source. This mode is usually preferred to be run with security options, though -disable-csrf is normal for server daemon mode, it is left enabled by default.

$ ./

To disable CSRF:

$ ./ -disable-csrf

Electron Desktop Client Mode

This mode configures itself via electron-main.js

Standalone Desktop Client Mode

This mode is configured by compiling with STANDALONE_CLIENT build tag. The configuration is handled in cmd/skycoin/skycoin.go

Wallet GUI Development

The compiled wallet source should be checked in to the repo, so that others do not need to install node to run the software.

Instructions for doing this:

Wallet GUI Development README


You can find information about how to work with translation files in the Translations README.


Update the version

  1. If the master branch has commits that are not in develop (e.g. due to a hotfix applied to master), merge master into develop
  2. Make sure the translations are up to date. See the i18n README for instructions on how to update translations and how to check if they are up to date.
  3. Compile the src/gui/static/dist/ to make sure that it is up to date (see Wallet GUI Development README)
  4. Update version strings to the new version in the following files: electron/package-lock.json, electron/package.json, electron/skycoin/current-skycoin.json, src/cli/cli.go, src/gui/static/src/current-skycoin.json, src/cli/integration/testdata/status*.golden, template/coin.template, files .
  5. If changes require a new database verification on the next upgrade, update src/skycoin/skycoin.go's DBVerifyCheckpointVersion value
  6. Update move the "unreleased" changes to the version and add the date
  7. Update the files in by following the metadata update procedure,
  8. Merge these changes to develop
  9. Follow the steps in pre-release testing
  10. Make a PR merging develop into master
  11. Review the PR and merge it
  12. Tag the master branch with the version number. Version tags start with v, e.g. v0.20.0. Sign the tag. If you have your GPG key in github, creating a release on the Github website will automatically tag the release. It can be tagged from the command line with git tag -as v0.20.0 $COMMIT_ID, but Github will not recognize it as a "release".
  13. Make sure that the client runs properly from the master branch
  14. Release builds are created and uploaded by travis. To do it manually, checkout the master branch and follow the create release builds instructions.

If there are problems discovered after merging to master, start over, and increment the 3rd version number. For example, v0.20.0 becomes v0.20.1, for minor fixes.

Pre-release testing

Performs these actions before releasing:

  • make check
  • make integration-test-live
  • make integration-test-live-disable-networking (requires node run with -disable-networking)
  • make integration-test-live-disable-csrf (requires node run with -disable-csrf)
  • make intergration-test-live-wallet (see live integration tests) both with an unencrypted and encrypted wallet
  • go run cmd/cli/cli.go checkdb against a fully synced database
  • go run cmd/cli/cli.go checkDBDecoding against a fully synced database
  • On all OSes, make sure that the client runs properly from the command line (./ and ./
  • Build the releases and make sure that the Electron client runs properly on Windows, Linux and macOS.
    • Use a clean data directory with no wallets or database to sync from scratch and verify the wallet setup wizard.
    • Load a test wallet with nonzero balance from seed to confirm wallet loading works
    • Send coins to another wallet to confirm spending works
    • Restart the client, confirm that it reloads properly
  • For both the Android and iOS mobile wallets, configure the node url to be and test all operations to ensure it will work with the new node version.

Creating release builds

Create Release builds.

Release signing

Releases are signed with this PGP key:


The fingerprint for this key is:

pub   ed25519 2017-09-01 [SC] [expires: 2023-03-18]
      10A7 22B7 6F2F FE7B D238  0222 5801 631B D27C 7874
uid                      GZ-C SKYCOIN <[email protected]>
sub   cv25519 2017-09-01 [E] [expires: 2023-03-18] account:

Follow the Tor Project's instructions for verifying signatures.

If you can't or don't want to import the keys from a keyserver, the signing key is available in the repo: gz-c.asc.

Releases and their signatures can be found on the releases page.

Instructions for generating a PGP key, publishing it, signing the tags and binaries:

Responsible Disclosure

Security flaws in skycoin source or infrastructure can be sent to [email protected]. Bounties are available for accepted critical bug reports.

PGP Key for signing:



Key ID: 0x5801631BD27C7874

The fingerprint for this key is:

pub   ed25519 2017-09-01 [SC] [expires: 2023-03-18]
      10A7 22B7 6F2F FE7B D238  0222 5801 631B D27C 7874
uid                      GZ-C SKYCOIN <[email protected]>
sub   cv25519 2017-09-01 [E] [expires: 2023-03-18] account:

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