Faygo uses the new architecture to make itself the most suitable Go Web framework for developping API. Just define a struct Handler, Faygo will automatically bind, verify the request parameters and generate the online API documentation.

Programming language: Go
License: Apache License 2.0
Latest version: v1.3.2

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Faygo is a fast and concise Go Web framework that can be used to develop high-performance web app(especially API) with fewer codes. Just define a struct Handler, Faygo will automatically bind/verify the request parameters and generate the online API doc. Go to <User Manual>


faygo index

faygo apidoc

faygo server

Latest version




Go Version ≥ 1.8

Quick Start

  • Way 1: download source
go get -u -v github.com/henrylee2cn/faygo
go get -u -v github.com/henrylee2cn/fay
        fay command [arguments]

The commands are:
        new        create, compile and run (monitor changes) a new faygo project
        run        compile and run (monitor changes) an any existing go project

fay new appname [apptpl]
        appname    specifies the path of the new faygo project
        apptpl     optionally, specifies the faygo project template type

fay run [appname]
        appname    optionally, specifies the path of the new project


  • One struct Handler can get more things:

    • Define Handler/Middleware
    • Bind and verify request parameters
    • Generate an online document for the Swagger 2.0 API
    • Database ORM mapping
  • Handler and Middleware are exactly the same, both implement the Handler interface (func orstruct), which together constitute the handler chain of the router.

  • Supports multiple network types:

Network types Configuration net_types
HTTP http
HTTPS/HTTP2(Let's Encrypt TLS) letsencrypt
HTTPS/HTTP2(Let's Encrypt TLS on UNIX socket) unix_letsencrypt
HTTP(UNIX socket) unix_http
HTTPS/HTTP2(TLS on UNIX socket) unix_https
  • Support single-service & single-listener, single-service & multi-listener, multi-service & multi-listener and so on. The config of multiple services is independent of each other
  • The high-performance router based on httprouter supports both chain and tree registration styles; supports flexible static file router (such as DirFS, RenderFS, MarkdownFS, etc.)
  • Support graceful shutdown and rebooting, provide fay tools which has new projects, hot compilation , meta programming function
  • Use the most powerful pongo2 as the HTML rendering engine
  • Support near-LRU memory caching (mainly used for static file cache)
  • Support cross-platform color log system, and has two output interface(console and file)
  • Support session management (If you use a persistent storage engine, you must use gob.Register() to register the relevant custom type before starting the service)
  • Support global gzip compression config
  • Support XSRF security filtering
  • Most features try to use simple ini configs to avoid unnecessary recompilation, and these profiles can be automatically assigned default values
  • Provide gorm, xorm, sqlx, directSQL, Websocket, ini, http client and many other commonly used expansion packages

faygo handler multi-usage

Simple example

package main

import (
    // "mime/multipart"

type Index struct {
    Id        int      `param:"<in:path> <required> <desc:ID> <range: 0:10>"`
    Title     string   `param:"<in:query> <nonzero>"`
    Paragraph []string `param:"<in:query> <name:p> <len: 1:10> <regexp: ^[\\w]*$>"`
    Cookie    string   `param:"<in:cookie> <name:faygoID>"`
    // Picture         *multipart.FileHeader `param:"<in:formData> <name:pic> <maxmb:30>"`

func (i *Index) Serve(ctx *faygo.Context) error {
    if ctx.CookieParam("faygoID") == "" {
        ctx.SetCookie("faygoID", time.Now().String())
    return ctx.JSON(200, i)

func main() {
    app := faygo.New("myapp", "0.1")

    // Register the route in a chain style
    app.GET("/index/:id", new(Index))

    // Register the route in a tree style
    // app.Route(
    //     app.NewGET("/index/:id", new(Index)),
    // )

    // Start the service

http GET:
        "Id": 1,
        "Title": "test",
        "Paragraph": [
        "Cookie": "2016-11-13 01:14:40.9038005 +0800 CST"

All samples

Handler and middleware

Handler and middleware are the same, both implemente Handler interface!

  • function type
// Page handler doesn't contains API doc description
func Page() faygo.HandlerFunc {
    return func(ctx *faygo.Context) error {
        return ctx.String(200, "faygo")

// Page2 handler contains API doc description
var Page2 = faygo.WrapDoc(Page(), "test page2 notes", "test")
  • struct type
// Param binds and validates the request parameters by Tags
type Param struct {
    Id    int    `param:"<in:path> <required> <desc:ID> <range: 0:10>"`
    Title string `param:"<in:query>"`

// Serve implemente Handler interface
func (p *Param) Serve(ctx *faygo.Context) error {
    return ctx.JSON(200,
            "Struct Params":    p,
            "Additional Param": ctx.PathParam("additional"),
        }, true)

// Doc implemente API Doc interface (optional)
func (p *Param) Doc() faygo.Doc {
    return faygo.Doc{
        // Add the API notes to the API doc
        Note: "param desc",
        // declare the response content format to the API doc
        Return: faygo.JSONMsg{
            Code: 1,
            Info: "success",
        // additional request parameter declarations to the API doc (optional)
        Params: []faygo.ParamInfo{
                Name:  "additional",
                In:    "path",
                Model: "a",
                Desc:  "defined by the `Doc()` method",

Filter function

The filter function must be HandleFunc type!

func Root2Index(ctx *faygo.Context) error {
    // Direct access to `/index` is not allowed
    if ctx.Path() == "/index" {
        return nil
    if ctx.Path() == "/" {
    return nil

Route registration

  • tree style
// New application object, params: name, version
var app1 = faygo.New("myapp1", "1.0")

// router
        app1.NewNamedGET("test page", "/page", Page()),
        app1.NewNamedGET("test page2", "/page2", Page2),
            app1.NewNamedGET("test param", "/param", &Param{
                // sets the default value in the API documentation for the request parameters (optional)
                Id:    1,
                Title: "test param",
  • chain style
// New application object, params: name, version
var app2 = faygo.New("myapp2", "1.0")

// router
app2.NamedGET("test page", "/page", Page())
app2.NamedGET("test page2", "/page2", Page2)
    app2.NamedGET("test param", "/param", &Param{
        // sets the default value in the API documentation for the request parameters(optional)
        Id:    1,
        Title: "test param",

Shutdown and reboot

  • shutdown gracefully
kill [pid]
  • reboot gracefully
kill -USR2 [pid]


  • Each instance of the application has a single config (file name format config/{appname}[_{version}].ini). Refer to the following:
net_types              = http|https              # List of network type: http | https | unix_http | unix_https | letsencrypt | unix_letsencrypt
addrs                  =|  # List of multiple listening addresses
tls_certfile           =                         # TLS certificate file path
tls_keyfile            =                         # TLS key file path
letsencrypt_dir        =                         # Let's Encrypt TLS certificate cache directory
unix_filemode          = 0666                    # File permissions for UNIX listener, requires octal number
http_redirect_https    = false                   # Redirect from 'http://hostname:port1' to 'https://hostname:port2'
read_timeout           = 0s                      # Maximum duration for reading the full; ns|µs|ms|s|m|h request (including body)
write_timeout          = 0s                      # Maximum duration for writing the full; ns|µs|ms|s|m|h response (including body)
multipart_maxmemory_mb = 32                      # Maximum size of memory that can be used when receiving uploaded files
slow_response_threshold= 0s                      # When response time > slow_response_threshold, log level   = 'WARNING'; 0 means not limited; ns|µs|ms|s|m|h
print_body             = false                   # Form requests are printed in JSON format, but other types are printed as-is

[router]                                         # Routing config section
redirect_trailing_slash   = true                 # Automatic redirection (for example, `/foo/` -> `/foo`)
redirect_fixed_path       = true                 # Tries to fix the current request path, if no handle is registered for it
handle_method_not_allowed = true                 # Returns 405 if the requested method does not exist, otherwise returns 404
handle_options            = true                 # Automatic response OPTIONS request, you can set the default Handler in Faygo
no_default_params         = false                # If true, don't assign default request parameter values based on initial parameter values of the routing handler
default_upload            = true                 # Automatically register the default router: /upload/*filepath
default_static            = true                 # Automatically register the default router: /static/*filepath

[xsrf]                                           # XSRF security section
enable        = false                            # Whether enabled or not
key           = faygoxsrf                        # Encryption key
expire_second = 3600                             # Expire of XSRF token

[session]                                        # Session section
enable                 = false                   # Whether enabled or not
provider               = memory                  # Data storage
name                   = faygosessionID          # The client stores the name of the cookie
provider_config        =                         # According to the different engine settings different config information
cookie_life_second     = 0                       # The default value is 0, which is the lifetime of the browser
gc_life_second         = 300                     # The interval between triggering the GC
max_life_second        = 3600                    # The session max lefetime
auto_setcookie         = true                    # Automatically set on the session cookie value, the general default true
domain                 =                         # The domain name that is allowed to access this cookie
enable_sid_in_header   = false                   # Whether to write a session ID to the header
name_in_header         = Faygosessionid          # The name of the header when the session ID is written to the header
enable_sid_in_urlquery = false                   # Whether to write the session ID to the URL Query params

[apidoc]                                         # API documentation section
enable      = true                               # Whether enabled or not
path        = /apidoc                            # The URL path
nolimit     = false                              # If true, access is not restricted
real_ip     = false                              # If true, means verifying the real IP of the visitor
whitelist   = 192.*|              # `whitelist=192.*|` means: only IP addresses that are prefixed with `192.` or equal to `` are allowed
desc        =                                    # Description of the application
email       =                                    # Technician's Email
terms_url   =                                    # Terms of service
license     =                                    # The license used by the API
license_url =                                    # The URL of the protocol content page
  • Only one global config is applied (config/__global__.ini). Refer to the following:
[cache]                                          # Cache section
enable         = false                           # Whether enabled or not
size_mb        = 32                              # Max size by MB for file cache, the cache size will be set to 512KB at minimum.
expire_second  = 60                              # Maximum duration for caching

[gzip]                                           # compression section
enable         = false                           # Whether enabled or not
min_length     = 20                              # The minimum length of content to be compressed
compress_level = 1                               # Non-file response Body's compression level is 0-9, but the files' always 9
methods        = GET                             # List of HTTP methods to compress. If not set, only GET requests are compressed.

[log]                                            # Log section
console_enable = true                            # Whether enabled or not console logger
console_level  = debug                           # Console logger level: critical | error | warning | notice | info | debug
file_enable    = true                            # Whether enabled or not file logger
file_level     = debug                           # File logger level: critical | error | warning | notice | info | debug
async_len      = 0                               # The length of asynchronous buffer, 0 means synchronization

Handler struct tags

tag key required value desc
param in only one path (position of param) if required is unsetted, auto set it. e.g. url: "http://www.abc.com/a/{path}"
param in only one query (position of param) e.g. url: "http://www.abc.com/a?b={query}"
param in only one formData (position of param) e.g. "request body: a=123&b={formData}"
param in only one body (position of param) request body can be any content
param in only one header (position of param) request header info
param in only one cookie (position of param) request cookie info, support: *http.Cookie,http.Cookie,string,[]byte
param name no (e.g.id) specify request param`s name
param required no request param is required
param desc no (e.g.id) request param description
param len no (e.g.3:6) length range [a,b] of param's value
param range no (e.g.0:10) numerical range [a,b] of param's value
param nonzero no param`s value can not be zero
param maxmb no (e.g.32) when request Content-Type is multipart/form-data, the max memory for body.(multi-param, whichever is greater)
param regexp no (e.g.^\\w+$) verify the value of the param with a regular expression(param value can not be null)
param err no (e.g.incorrect password format) the custom error for binding or validating


  • the binding object must be a struct pointer
  • in addition to *multipart.FileHeader, the binding struct's field can not be a pointer
  • if the param tag is not exist, anonymous field will be parsed
  • when the param's position(in) is formData and the field's type is *multipart.FileHeader, multipart.FileHeader, []*multipart.FileHeader or []multipart.FileHeader, the param receives file uploaded
  • if param's position(in) is cookie, field's type must be *http.Cookie or http.Cookie
  • param tags in(formData) and in(body) can not exist at the same time
  • there should not be more than one in(body) param tag

Handler struct fields type

base slice special
string []string [][]byte
byte []byte [][]uint8
uint8 []uint8 *multipart.FileHeader (only for formData param)
bool []bool []*multipart.FileHeader (only for formData param)
int []int *http.Cookie (only for net/http's cookie param)
int8 []int8 http.Cookie (only for net/http's cookie param)
int16 []int16 struct (struct type only for body param or as an anonymous field to extend params)
int32 []int32
int64 []int64
uint8 []uint8
uint16 []uint16
uint32 []uint32
uint64 []uint64
float32 []float32
float64 []float64

Expansion package

package summary import path
barcode github.com/henrylee2cn/faygo/ext/barcode
Bit unit conversion github.com/henrylee2cn/faygo/ext/bitconv
gorm(DB ORM) github.com/henrylee2cn/faygo/ext/db/gorm
sqlx(DB ext) github.com/henrylee2cn/faygo/ext/db/sqlx
xorm(DB ORM) github.com/henrylee2cn/faygo/ext/db/xorm
directSQL(Configured SQL engine) github.com/henrylee2cn/faygo/ext/db/directsql
One-time Password github.com/henrylee2cn/faygo/ext/otp
UUID github.com/henrylee2cn/faygo/ext/uuid
Websocket github.com/henrylee2cn/faygo/ext/websocket
ini github.com/henrylee2cn/faygo/ini
cron github.com/henrylee2cn/faygo/ext/cron
task github.com/henrylee2cn/faygo/ext/task
http client github.com/henrylee2cn/faygo/ext/surfer

Know Cases

Product Name Web/App Server Home Page
盯房 App https://www.df-house.com
eTrade App https://fir.im/ejy
OneFor App https://fir.im/eqb
杰运好车 App https://itunes.apple.com/cn/app/%E6%9D%B0%E8%BF%90%E5%A5%BD%E8%BD%A6/id1301132479?mt=8

Note: Sorted in alphabetical order

Business Users



Faygo is under Apache v2 License. See the LICENSE file for the full license text

*Note that all licence references and agreements mentioned in the Faygo README section above are relevant to that project's source code only.