diff --git a/.gitignore b/.gitignore
index d3d6d37..7240670 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,6 @@
 
+config.json
+
 data/*
 testdata
 
diff --git a/README.md b/README.md
index d8904ce..a0fab65 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,42 @@ Inspect how it's used on https://brainbaking.com/ - usually, a `<link/>` in your
 
 If you want to support the older pingback protocol, you can leverage webmenton.io's forward capabilities. Although I developed this primarily because webmention.io is _not_ reliable - you've been warned. 
 
+## Building and running
+
+Well, that's easy!
+
+1. Build: `go build`
+2. Run: `./go-jamming`
+3. ???
+4. Profit!
+
+## Configuration
+
+Place a `config.json` file in the same directory that looks like this:
+
+```json
+{
+  "port": 1337,
+  "host": "localhost",
+  "token": "sometoken",
+  "dataPath": "data",
+  "utcOffset": 60,
+  "allowedWebmentionSources":  [
+    "blah.com"
+  ],
+  "disallowedWebmentionDomains":  [
+    "youtube.com"
+  ]
+}
+```
+
+- port, host: http server params
+- token, allowedWebmentionSources: see below, used for authentication
+- utcOffset: offset in minutes for date processing, starting from UTC time.
+- dataPath: path to store all mentions as md5-encoded JSON filenames.
+
+If a config file is missing, or required keys are missing, a warning will be generated and default values will be used instead. See `common/config.go`.
+
 ## What's in it?
 
 ### 1. Webmentions
@@ -38,11 +74,11 @@ Accepted form format:
     target=https://aaronpk.example/post-by-aaron
 ```
 
-Will result in a `202 Accepted` - it handles things async. Stores in `.json` files in `data/domain`. 
+Will result in a `202 Accepted` - it handles things async. Stores in `.json` files in `[dataPath]/domain`. 
 
 #### 1.2 `GET /webmention/:domain/:token`
 
-Retrieves a JSON array with relevant webmentions stored for that domain. The token should match. See `config.js` to fiddle with it yourself. Environment variables are supported, although I haven't used them yet. 
+Retrieves a JSON array with relevant webmentions stored for that domain. The token should match. See configuration to fiddle with it yourself. Environment variables are supported, although I haven't used them yet. 
 
 #### 1.3 `PUT /webmention/:domain/:token`
 
@@ -95,8 +131,3 @@ Will result in a `200 OK` - that returns XML according to [The W3 pingback XML-R
 
 Happens automatically through `PUT /webmention/:domain/:token`! Links that are discovered as `rel="pingback"` that **do not** already have a webmention link will be processed as XML-RPC requests to be send. 
 
-
-## TODOs
-
-- `published` date is not well-formatted and blindly taken over from feed
-- Implement a Brid.gy-like system that converts links from domains in the config found on [public Mastodon timelines](https://docs.joinmastodon.org/methods/timelines/) into webmentions. (And check if it's ok to only use the public line)
diff --git a/common/config.go b/common/config.go
index f6df1f5..91bb649 100644
--- a/common/config.go
+++ b/common/config.go
@@ -1,21 +1,39 @@
 package common
 
 import (
+	"encoding/json"
 	"errors"
+	"io/ioutil"
 	"os"
-	"strconv"
 	"strings"
 
 	"github.com/rs/zerolog/log"
 )
 
 type Config struct {
-	Port                        int
-	Token                       string
-	UtcOffset                   int
-	DataPath                    string
-	AllowedWebmentionSources    []string
-	DisallowedWebmentionDomains []string
+	Port                        int      `json:"port"`
+	Token                       string   `json:"token"`
+	UtcOffset                   int      `json:"utcOffset"`
+	DataPath                    string   `json:"dataPath"`
+	AllowedWebmentionSources    []string `json:"allowedWebmentionSources"`
+	DisallowedWebmentionDomains []string `json:"disallowedWebmentionDomains"`
+}
+
+func (c *Config) missingKeys() []string {
+	keys := []string{}
+	if c.Port == 0 {
+		keys = append(keys, "port")
+	}
+	if c.Token == "" {
+		keys = append(keys, "token")
+	}
+	if c.DataPath == "" {
+		keys = append(keys, "dataPath")
+	}
+	if len(c.AllowedWebmentionSources) == 0 {
+		keys = append(keys, "allowedWebmentionSources")
+	}
+	return keys
 }
 
 func (c *Config) ContainsDisallowedDomain(url string) bool {
@@ -53,23 +71,33 @@ func (c *Config) SetupDataDirs() {
 }
 
 func Configure() (c *Config) {
-	portstr := os.Getenv("PORT")
-	port, err := strconv.Atoi(portstr)
+	confData, err := ioutil.ReadFile("config.json")
 	if err != nil {
-		port = 1337
-	}
-	token := os.Getenv("TOKEN")
-	if token == "" {
-		token = "miauwkes"
+		log.Warn().Msg("No config.json file found, reverting to defaults...")
+		return defaultConfig()
 	}
 
-	c = &Config{
-		Port:                        port,
-		Token:                       token,
+	conf := &Config{}
+	err = json.Unmarshal(confData, conf)
+	if err != nil {
+		log.Warn().Msg("config.json malformed JSON, reverting to defaults...")
+		return defaultConfig()
+	}
+	someMissingKeys := conf.missingKeys()
+	if len(someMissingKeys) > 0 {
+		log.Warn().Str("keys", strings.Join(someMissingKeys, ", ")).Msg("config.json is missing required keys, reverting to defaults...")
+		return defaultConfig()
+	}
+	return conf
+}
+
+func defaultConfig() *Config {
+	return &Config{
+		Port:                        1337,
+		Token:                       "miauwkes",
 		UtcOffset:                   60,
 		DataPath:                    "data",
 		AllowedWebmentionSources:    []string{"brainbaking.com", "jefklakscodex.com"},
 		DisallowedWebmentionDomains: []string{"youtube.com"},
 	}
-	return
 }