diff --git a/extra/crontab/authors.txt b/extra/crontab/authors.txt
new file mode 100644
index 0000000000..e091bb8164
--- /dev/null
+++ b/extra/crontab/authors.txt
@@ -0,0 +1 @@
+John Benediktsson
diff --git a/extra/crontab/crontab-tests.factor b/extra/crontab/crontab-tests.factor
new file mode 100644
index 0000000000..e0ba8d6dea
--- /dev/null
+++ b/extra/crontab/crontab-tests.factor
@@ -0,0 +1,22 @@
+USING: calendar crontab kernel tools.test ;
+
+{
+    T{ timestamp
+        { year 2018 }
+        { month 3 }
+        { day 9 }
+        { hour 12 }
+        { minute 23 }
+        { gmt-offset T{ duration { hour -8 } } }
+    }
+} [
+    "23 0-20/2 * * *" parse-cronentry
+    T{ timestamp
+        { year 2018 }
+        { month 3 }
+        { day 9 }
+        { hour 12 }
+        { minute 6 }
+        { gmt-offset T{ duration { hour -8 } } }
+    } [ next-time-after ] keep
+] unit-test
diff --git a/extra/crontab/crontab.factor b/extra/crontab/crontab.factor
new file mode 100644
index 0000000000..c214cec8fb
--- /dev/null
+++ b/extra/crontab/crontab.factor
@@ -0,0 +1,104 @@
+! Copyright (C) 2018 John Benediktsson
+! See http://factorcode.org/license.txt for BSD license
+
+USING: accessors arrays ascii assocs calendar calendar.english
+calendar.private combinators io kernel literals locals math
+math.order math.parser math.ranges sequences splitting ;
+
+IN: crontab
+
+:: parse-value ( value quot: ( value -- value' ) seq -- value )
+    value {
+        { [ CHAR: , over member? ] [
+            "," split [ quot seq parse-value ] map concat ] }
+        { [ dup "*" = ] [ drop seq ] }
+        { [ CHAR: / over member? ] [
+            "/" split1 [ quot seq parse-value 0 over length 1 - ] dip
+            string>number <range> swap nths ] }
+        { [ CHAR: - over member? ] [
+            "-" split1 quot bi@ [a,b] ] }
+        [ quot call 1array ]
+    } cond ; inline recursive
+
+: parse-day ( str -- n )
+    dup string>number [ ] [
+        >lower $[ day-abbreviations3 [ >lower ] map ] index
+    ] ?if ;
+
+: parse-month ( str -- n )
+    dup string>number [ ] [
+        >lower $[ month-abbreviations [ >lower ] map ] index
+    ] ?if ;
+
+TUPLE: cronentry minutes hours days months days-of-week command ;
+
+CONSTANT: aliases H{
+    { "@yearly"   "0 0 1 1 *" }
+    { "@annually" "0 0 1 1 *" }
+    { "@monthly"  "0 0 1 * *" }
+    { "@weekly"   "0 0 * * 0" }
+    { "@daily"    "0 0 * * *" }
+    { "@midnight" "0 0 * * *" }
+    { "@hourly"   "0 * * * *" }
+}
+
+: parse-cronentry ( entry -- cronentry )
+    " " split1 [ aliases ?at drop ] dip " " glue
+    " " split1 " " split1 " " split1 " " split1 " " split1 {
+        [ [ string>number ] T{ range f 0 60 1 } parse-value ]
+        [ [ string>number ] T{ range f 0 24 1 } parse-value ]
+        [ [ string>number ] T{ range f 0 31 1 } parse-value ]
+        [ [ parse-month ] T{ range f 0 12 1 } parse-value ]
+        [ [ parse-day ] T{ range f 0 7 1 } parse-value ]
+        [ ]
+    } spread cronentry boa ;
+
+:: next-time-after ( cronentry timestamp -- )
+
+    timestamp month>> :> month
+    cronentry months>> [ month >= ] find nip [
+        dup month = [ drop f ] [ timestamp month<< t ] if
+    ] [
+        timestamp cronentry months>> first >>month 1 +year
+    ] if* [ cronentry timestamp next-time-after ] when
+
+    timestamp hour>> :> hour
+    cronentry hours>> [ hour >= ] find nip [
+        dup hour = [ drop f ] [
+            timestamp hour<< 0 timestamp minute<< t
+        ] if
+    ] [
+        timestamp cronentry hours>> first >>hour 1 +day
+    ] if* [ cronentry timestamp next-time-after ] when
+
+    timestamp minute>> :> minute
+    cronentry minutes>> [ minute >= ] find nip [
+        dup minute = [ drop f ] [ timestamp minute<< t ] if
+    ] [
+        timestamp cronentry minutes>> first >>minute 1 +hour
+    ] if* [ cronentry timestamp next-time-after ] when
+
+    timestamp day-of-week :> weekday
+    cronentry days-of-week>> [ weekday >= ] find nip [
+        cronentry days-of-week>> first 7 +
+    ] unless* weekday -
+
+    timestamp day>> :> day
+    cronentry days>> [ day >= ] find nip [
+        day -
+    ] [
+        timestamp 1 months time+
+        cronentry days>> first >>day
+        day-of-year timestamp day-of-year -
+    ] if*
+
+    min [
+        timestamp swap +day drop
+        cronentry timestamp next-time-after
+    ] unless-zero ;
+
+: next-time ( cronentry -- timestamp )
+    now 0 >>second [ next-time-after ] keep ;
+
+: parse-crontab ( -- entries )
+    lines [ [ f ] [ parse-cronentry ] if-empty ] map harvest ;
diff --git a/extra/crontab/summary.txt b/extra/crontab/summary.txt
new file mode 100644
index 0000000000..c754345ba1
--- /dev/null
+++ b/extra/crontab/summary.txt
@@ -0,0 +1 @@
+Parser for crontab files