diff --git a/src/optparse.c b/src/optparse.c
new file mode 100644
index 0000000..867b635
--- /dev/null
+++ b/src/optparse.c
@@ -0,0 +1,391 @@
+/** @file
+    Option parsing functions to complement getopt.
+
+    Copyright (C) 2017 Christian Zuckschwerdt
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+*/
+
+#include "optparse.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <string.h>
+
+int atobv(char *arg, int def)
+{
+    if (!arg)
+        return def;
+    if (!strcasecmp(arg, "true") || !strcasecmp(arg, "yes") || !strcasecmp(arg, "on") || !strcasecmp(arg, "enable"))
+        return 1;
+    return atoi(arg);
+}
+
+int atoiv(char *arg, int def)
+{
+    if (!arg)
+        return def;
+    char *endptr;
+    int val = strtol(arg, &endptr, 10);
+    if (arg == endptr)
+        return def;
+    return val;
+}
+
+char *arg_param(char *arg)
+{
+    if (!arg)
+        return NULL;
+    char *p = strchr(arg, ':');
+    char *c = strchr(arg, ',');
+    if (p && (!c || p < c))
+        return ++p;
+    else if (c)
+        return c;
+    else
+        return p;
+}
+
+double arg_float(const char *str, const char *error_hint)
+{
+    if (!str) {
+        fprintf(stderr, "%smissing number argument\n", error_hint);
+        exit(1);
+    }
+
+    if (!*str) {
+        fprintf(stderr, "%sempty number argument\n", error_hint);
+        exit(1);
+    }
+
+    // allow whitespace and equals char
+    while (*str == ' ' || *str == '=')
+        ++str;
+
+    char *endptr;
+    double val = strtod(str, &endptr);
+
+    if (str == endptr) {
+        fprintf(stderr, "%sinvalid number argument (%s)\n", error_hint, str);
+        exit(1);
+    }
+
+    return val;
+}
+
+char *hostport_param(char *param, char **host, char **port)
+{
+    if (param && *param) {
+        if (param[0] == '/' && param[1] == '/') {
+            param += 2;
+        }
+        if (*param != ':' && *param != ',') {
+            *host = param;
+            if (*param == '[') {
+                (*host)++;
+                param = strchr(param, ']');
+                if (param) {
+                    *param++ = '\0';
+                }
+                else {
+                    fprintf(stderr, "Malformed Ipv6 address!\n");
+                    exit(1);
+                }
+            }
+        }
+        char *colon = strchr(param, ':');
+        char *comma = strchr(param, ',');
+        if (colon && (!comma || colon < comma)) {
+            *colon++ = '\0';
+            *port    = colon;
+        }
+        if (comma) {
+            *comma++ = '\0';
+            return comma;
+        }
+    }
+    return NULL;
+}
+
+uint32_t atouint32_metric(const char *str, const char *error_hint)
+{
+    if (!str) {
+        fprintf(stderr, "%smissing number argument\n", error_hint);
+        exit(1);
+    }
+
+    if (!*str) {
+        fprintf(stderr, "%sempty number argument\n", error_hint);
+        exit(1);
+    }
+
+    char *endptr;
+    double val = strtod(str, &endptr);
+
+    if (str == endptr) {
+        fprintf(stderr, "%sinvalid number argument (%s)\n", error_hint, str);
+        exit(1);
+    }
+
+    if (val < 0.0) {
+        fprintf(stderr, "%snon-negative number argument expected (%f)\n", error_hint, val);
+        exit(1);
+    }
+
+    // allow whitespace before suffix
+    while (*endptr == ' ' || *endptr == '\t')
+        ++endptr;
+
+    switch (*endptr) {
+        case '\0':
+            break;
+        case 'k':
+        case 'K':
+            val *= 1e3;
+            break;
+        case 'M':
+        case 'm':
+            val *= 1e6;
+            break;
+        case 'G':
+        case 'g':
+            val *= 1e9;
+            break;
+        default:
+            fprintf(stderr, "%sunknown number suffix (%s)\n", error_hint, endptr);
+            exit(1);
+    }
+
+    if (val > UINT32_MAX) {
+        fprintf(stderr, "%snumber argument too big (%f)\n", error_hint, val);
+        exit(1);
+    }
+
+    val += 1e-5; // rounding (e.g. 4123456789.99999)
+    if (val - (uint32_t)val > 2e-5) {
+        fprintf(stderr, "%sdecimal fraction (%f) did you forget k, M, or G suffix?\n", error_hint, val - (uint32_t)val);
+    }
+
+    return (uint32_t)val;
+}
+
+int atoi_time(const char *str, const char *error_hint)
+{
+    if (!str) {
+        fprintf(stderr, "%smissing time argument\n", error_hint);
+        exit(1);
+    }
+
+    if (!*str) {
+        fprintf(stderr, "%sempty time argument\n", error_hint);
+        exit(1);
+    }
+
+    char *endptr    = NULL;
+    double val      = 0.0;
+    unsigned colons = 0;
+
+    do {
+        double num = strtod(str, &endptr);
+
+        if (!endptr || str == endptr) {
+            fprintf(stderr, "%sinvalid time argument (%s)\n", error_hint, str);
+            exit(1);
+        }
+
+        // allow whitespace before suffix
+        while (*endptr == ' ' || *endptr == '\t')
+            ++endptr;
+
+        switch (*endptr) {
+        case '\0':
+            if (colons == 0) {
+                // assume seconds
+                val += num;
+                break;
+            }
+            // intentional fallthrough
+        case ':':
+            ++colons;
+            if (colons == 1)
+                val += num * 60 * 60;
+            else if (colons == 2)
+                val += num * 60;
+            else if (colons == 3)
+                val += num;
+            else {
+                fprintf(stderr, "%stoo many colons (use HH:MM[:SS]))\n", error_hint);
+                exit(1);
+            }
+            if (*endptr)
+                ++endptr;
+            break;
+        case 's':
+        case 'S':
+            val += num;
+            ++endptr;
+            break;
+        case 'm':
+        case 'M':
+            val += num * 60;
+            ++endptr;
+            break;
+        case 'h':
+        case 'H':
+            val += num * 60 * 60;
+            ++endptr;
+            break;
+        case 'd':
+        case 'D':
+            val += num * 60 * 60 * 24;
+            ++endptr;
+            break;
+        default:
+            fprintf(stderr, "%sunknown time suffix (%s)\n", error_hint, endptr);
+            exit(1);
+        }
+
+        // chew up any remaining whitespace
+        while (*endptr == ' ' || *endptr == '\t')
+            ++endptr;
+        str = endptr;
+
+    } while (*endptr);
+
+    if (val > INT_MAX || val < INT_MIN) {
+        fprintf(stderr, "%stime argument too big (%f)\n", error_hint, val);
+        exit(1);
+    }
+
+    if (val < 0) {
+        val -= 1e-5; // rounding (e.g. -4123456789.99999)
+    }
+    else {
+        val += 1e-5; // rounding (e.g. 4123456789.99999)
+    }
+    if (val - (int)(val) > 2e-5) {
+        fprintf(stderr, "%sdecimal fraction (%f) did you forget m, or h suffix?\n", error_hint, val - (uint32_t)val);
+    }
+
+    return (int)val;
+}
+
+char *asepc(char **stringp, char delim)
+{
+    if (!stringp || !*stringp) return NULL;
+    char *s = strchr(*stringp, delim);
+    if (s) *s++ = '\0';
+    char *p = *stringp;
+    *stringp = s;
+    return p;
+}
+
+char *getkwargs(char **s, char **key, char **val)
+{
+    char *v = asepc(s, ',');
+    char *k = asepc(&v, '=');
+    if (key) *key = k;
+    if (val) *val = v;
+    return k;
+}
+
+char *trim_ws(char *str)
+{
+    if (!str || !*str)
+        return str;
+    while (*str == ' ' || *str == '\t' || *str == '\r' || *str == '\n')
+        ++str;
+    char *e = str; // end pointer (last non ws)
+    char *p = str; // scanning pointer
+    while (*p) {
+        while (*p == ' ' || *p == '\t' || *p == '\r' || *p == '\n')
+            ++p;
+        if (*p)
+            e = p++;
+    }
+    *++e = '\0';
+    return str;
+}
+
+char *remove_ws(char *str)
+{
+    if (!str)
+        return str;
+    char *d = str; // dst pointer
+    char *s = str; // src pointer
+    while (*s) {
+        while (*s == ' ' || *s == '\t' || *s == '\r' || *s == '\n')
+            ++s;
+        if (*s)
+            *d++ = *s++;
+    }
+    *d++ = '\0';
+    return str;
+}
+
+// Unit testing
+#ifdef _TEST
+#define ASSERT_EQUALS(a,b)                                  \
+    do {                                                    \
+        if ((a) == (b))                                     \
+            ++passed;                                       \
+        else {                                              \
+            ++failed;                                       \
+            fprintf(stderr, "FAIL: %d <> %d\n", (a), (b));  \
+        }                                                   \
+    } while (0)
+
+int main(void)
+{
+    unsigned passed = 0;
+    unsigned failed = 0;
+
+    fprintf(stderr, "optparse:: atouint32_metric\n");
+    ASSERT_EQUALS(atouint32_metric("0", ""), 0);
+    ASSERT_EQUALS(atouint32_metric("1", ""), 1);
+    ASSERT_EQUALS(atouint32_metric("0.0", ""), 0);
+    ASSERT_EQUALS(atouint32_metric("1.0", ""), 1);
+    ASSERT_EQUALS(atouint32_metric("1.024k", ""), 1024);
+    ASSERT_EQUALS(atouint32_metric("433.92M", ""), 433920000);
+    ASSERT_EQUALS(atouint32_metric("433.94M", ""), 433940000);
+    ASSERT_EQUALS(atouint32_metric(" +1 G ", ""), 1000000000);
+	ASSERT_EQUALS(atouint32_metric("1e6", ""), 1000000);
+
+    fprintf(stderr, "optparse:: atoi_time\n");
+    ASSERT_EQUALS(atoi_time("0", ""), 0);
+    ASSERT_EQUALS(atoi_time("1", ""), 1);
+    ASSERT_EQUALS(atoi_time("0.0", ""), 0);
+    ASSERT_EQUALS(atoi_time("1.0", ""), 1);
+    ASSERT_EQUALS(atoi_time("1s", ""), 1);
+    ASSERT_EQUALS(atoi_time("2d", ""), 2 * 60 * 60 * 24);
+    ASSERT_EQUALS(atoi_time("2h", ""), 2 * 60 * 60);
+    ASSERT_EQUALS(atoi_time("2m", ""), 2 * 60);
+    ASSERT_EQUALS(atoi_time("2s", ""), 2);
+    ASSERT_EQUALS(atoi_time("2D", ""), 2 * 60 * 60 * 24);
+    ASSERT_EQUALS(atoi_time("2H", ""), 2 * 60 * 60);
+    ASSERT_EQUALS(atoi_time("2M", ""), 2 * 60);
+    ASSERT_EQUALS(atoi_time("2S", ""), 2);
+    ASSERT_EQUALS(atoi_time("2h3m4s", ""), 2 * 60 * 60 + 3 * 60 + 4);
+    ASSERT_EQUALS(atoi_time("2h 3m 4s", ""), 2 * 60 * 60 + 3 * 60 + 4);
+    ASSERT_EQUALS(atoi_time("2h3h 3m 4s 5", ""), 5 * 60 * 60 + 3 * 60 + 9);
+    ASSERT_EQUALS(atoi_time(" 2m ", ""), 2 * 60);
+    ASSERT_EQUALS(atoi_time("2 m", ""), 2 * 60);
+    ASSERT_EQUALS(atoi_time("  2  m  ", ""), 2 * 60);
+    ASSERT_EQUALS(atoi_time("-1m", ""), -60);
+    ASSERT_EQUALS(atoi_time("1h-15m", ""), 45 * 60);
+
+    ASSERT_EQUALS(atoi_time("2:3", ""), 2 * 60 * 60 + 3 * 60);
+    ASSERT_EQUALS(atoi_time("2:3:4", ""), 2 * 60 * 60 + 3 * 60 + 4);
+    ASSERT_EQUALS(atoi_time("02:03", ""), 2 * 60 * 60 + 3 * 60);
+    ASSERT_EQUALS(atoi_time("02:03:04", ""), 2 * 60 * 60 + 3 * 60 + 4);
+    ASSERT_EQUALS(atoi_time(" 2 : 3 ", ""), 2 * 60 * 60 + 3 * 60);
+    ASSERT_EQUALS(atoi_time(" 2 : 3 : 4 ", ""), 2 * 60 * 60 + 3 * 60 + 4);
+
+    fprintf(stderr, "optparse:: test (%u/%u) passed, (%u) failed.\n", passed, passed + failed, failed);
+
+    return failed;
+}
+#endif /* _TEST */
diff --git a/src/optparse.h b/src/optparse.h
new file mode 100644
index 0000000..6325693
--- /dev/null
+++ b/src/optparse.h
@@ -0,0 +1,105 @@
+/** @file
+    Option parsing functions to complement getopt.
+
+    Copyright (C) 2017 Christian Zuckschwerdt
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+*/
+
+#ifndef INCLUDE_OPTPARSE_H_
+#define INCLUDE_OPTPARSE_H_
+
+#include <stdint.h>
+
+// makes strcasecmp() and strncasecmp() available when including optparse.h
+#ifdef _MSC_VER
+    #include <string.h>
+    #define strcasecmp(s1,s2)     _stricmp(s1,s2)
+    #define strncasecmp(s1,s2,n)  _strnicmp(s1,s2,n)
+#else
+    #include <strings.h>
+#endif
+
+/// Convert string to bool with fallback default.
+/// Parses "true", "yes", "on", "enable" (not case-sensitive) to 1, atoi() otherwise.
+int atobv(char *arg, int def);
+
+/// Convert string to int with fallback default.
+int atoiv(char *arg, int def);
+
+/// Get the next colon or comma separated arg, NULL otherwise.
+/// Returns string including comma if a comma is found first,
+/// otherwise string after colon if found, NULL otherwise.
+char *arg_param(char *arg);
+
+/// Convert a string with optional leading equals char to a double.
+///
+/// Parse errors will fprintf(stderr, ...) and exit(1).
+///
+/// @param str character string to parse
+/// @param error_hint prepended to error output
+/// @return parsed number value
+double arg_float(const char *str, const char *error_hint);
+
+/// Parse param string to host and port.
+/// E.g. ":514", "localhost", "[::1]", "127.0.0.1:514", "[::1]:514",
+/// also "//localhost", "//localhost:514", "//:514".
+/// Host or port are terminated at a comma, if found.
+/// @return the remaining options
+char *hostport_param(char *param, char **host, char **port);
+
+/// Convert a string to an unsigned integer, uses strtod() and accepts
+/// metric suffixes of 'k', 'M', and 'G' (also 'K', 'm', and 'g').
+///
+/// Parse errors will fprintf(stderr, ...) and exit(1).
+///
+/// @param str character string to parse
+/// @param error_hint prepended to error output
+/// @return parsed number value
+uint32_t atouint32_metric(const char *str, const char *error_hint);
+
+/// Convert a string to an integer, uses strtod() and accepts
+/// time suffixes of 'd', 'h', 'm', and 's' (also 'D', 'H', 'M', and 'S'),
+/// or the form hours:minutes[:seconds].
+///
+/// Parse errors will fprintf(stderr, ...) and exit(1).
+///
+/// @param str character string to parse
+/// @param error_hint prepended to error output
+/// @return parsed number value
+int atoi_time(const char *str, const char *error_hint);
+
+/// Similar to strsep.
+///
+/// @param[in,out] stringp String to parse inplace
+/// @param delim the delimiter character
+/// @return the original value of *stringp
+char *asepc(char **stringp, char delim);
+
+/// Parse a comma-separated list of key/value pairs into kwargs.
+///
+/// The input string will be modified and the pointer advanced.
+/// The key and val pointers will be into the original string.
+///
+/// @param[in,out] s String of key=value pairs, separated by commas
+/// @param[out] key keyword argument if found, NULL otherwise
+/// @param[out] val value if found, NULL otherwise
+/// @return the original value of *stringp (the keyword found)
+char *getkwargs(char **s, char **key, char **val);
+
+/// Trim left and right whitespace in string.
+///
+/// @param[in,out] str String to change inplace
+/// @return the trimmed value of str
+char *trim_ws(char *str);
+
+/// Remove all whitespace from string.
+///
+/// @param[in,out] str String to change inplace
+/// @return the stripped value of str
+char *remove_ws(char *str);
+
+#endif /* INCLUDE_OPTPARSE_H_ */