# Introduction Measures [time-to-first-byte](https://en.wikipedia.org/wiki/Time_to_first_byte) for single or multiple URLs. Can show you quickest, slowest & median TTFB values plus optionally log all response headers. ``` Usage: ttfb [options] url [url...] -d debug -l (infers -d) log response headers. Defaults to ./curl.log -n of times to test time to first byte -v verbose output. Show response breakdown (DNS lookup, TLS handshake etc) ``` Implicitly follows a redirection chain using curl's `-L` option. Can log all response headers (the default log file is `./curl.log`) by calling with `-d`. Override the default log file by specifying `-l /some/file`. Get quickest, slowest and median TTFB values by specifying the number of times to call a URL; use `-n2` for 2 tests, `-n5` for 5 and so on. Uses the calculation `%{time_starttransfer¹} - %{time_appconnect²}` which doesn't include any connection overhead, to better approximate [devtool’s TTFB figure](https://developers.google.com/web/tools/chrome-devtools/network/understanding-resource-timing#slow_time_to_first_byte). ¹ [`time_starttransfer`](https://github.com/curl/curl/blob/e431daf013ea04cb1a988a2009d820224ef5fb79/docs/cmdline-opts/write-out.d#L141-L144) > The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result. ² [`time_appconnect`](https://github.com/curl/curl/blob/e431daf013ea04cb1a988a2009d820224ef5fb79/docs/cmdline-opts/write-out.d#L118-L120) >The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. # Genesis Based on a [gist](https://gist.github.com/sandeepraju/1f5fbdbdd89551ba7925abe2645f92b5) by https://github.com/sandeepraju Modified by jay@gooby.org, [@jaygooby](https://twitter.com/jaygooby) # Usage ``` Usage: ttfb [options] url [url...] -d debug -l (infers -d) log response headers. Defaults to ./curl.log -n of times to test time to first byte -v verbose output. Show response breakdown (DNS lookup, TLS handshake etc) ``` ## Examples Basic usage: ``` $ ttfb example.com .227436 ``` Basic usage with verbose response breakdown: ``` $ ttfb -v https://example.com DNS lookup: 0.005152 TLS handshake: 0.000000 TTFB including connection: 0.200831 TTFB: .200831 Total time: 0.201132 ``` Test multiple times: ``` $ ttfb -n 5 example.com/example/url ..... fastest .177263 slowest .214302 median .179957 ``` Test multiple URLs: ``` $ ttfb bbc.co.uk news.bbc.co.uk bbc.co.uk .049985 news.bbc.co.uk .054122 ``` Test multiple URLs, multiple times: ``` $ ttfb -n 5 bbc.co.uk news.bbc.co.uk ..... ..... bbc.co.uk fastest .030936 slowest .057755 median .034663 news.bbc.co.uk fastest .031413 slowest .182791 median .035001 ``` Verbose response breakdown when multiple tests specified: ``` $ ttfb -v -n 5 bbc.co.uk DNS lookup: 0.005335 TLS handshake: 0.102314 TTFB including connection: 0.148328 TTFB: .046014 Total time: 0.646115 DNS lookup: 0.005322 TLS handshake: 0.102609 TTFB including connection: 0.150693 TTFB: .048084 Total time: 0.644611 DNS lookup: 0.004277 TLS handshake: 0.102066 TTFB including connection: 0.172199 TTFB: .070133 Total time: 1.196256 DNS lookup: 0.004444 TLS handshake: 0.107375 TTFB including connection: 0.160771 TTFB: .053396 Total time: 0.637290 DNS lookup: 0.005352 TLS handshake: 0.118882 TTFB including connection: 0.168772 TTFB: .049890 Total time: 0.653761 fastest .046014 slowest .070133 median .049890 ``` Log all the response headers for multiple tests to multiple URLs: ``` ttfb -d -n 2 bbc.co.uk https://www.bbc.co.uk/weather .. .. bbc.co.uk fastest .027550 slowest .055215 median .041382 https://www.bbc.co.uk/weather fastest .101020 slowest .297923 median .199471 $ ls *.log bbc_co_uk-curl.log https___www_bbc_co_uk_weather-curl.log $ cat https___www_bbc_co_uk_weather-curl.log HTTP/2 200 server: openresty x-cache-action: MISS vary: Accept-Encoding,X-BBC-Edge-Cache,X-BBC-Edge-Scheme,X-CDN x-cache-age: 0 cache-control: private, stale-while-revalidate=10, max-age=0, must-revalidate content-type: text/html;charset=utf-8 x-mrid: w1 date: Thu, 11 Apr 2019 17:08:07 GMT x-xss-protection: 1; mode=block x-content-type-options: nosniff x-lb-nocache: true x-msig: 24e37f81323984e4e45b8048f9e3c94a x-frame-options: SAMEORIGIN content-length: 1077454 HTTP/2 200 server: openresty x-cache-action: MISS vary: Accept-Encoding,X-BBC-Edge-Cache,X-BBC-Edge-Scheme,X-CDN x-cache-age: 0 cache-control: private, stale-while-revalidate=10, max-age=0, must-revalidate content-type: text/html;charset=utf-8 x-mrid: w1 date: Thu, 11 Apr 2019 17:08:08 GMT x-xss-protection: 1; mode=block x-content-type-options: nosniff x-lb-nocache: true x-msig: 24e37f81323984e4e45b8048f9e3c94a x-frame-options: SAMEORIGIN content-length: 1077454 ``` # More detail on time-to-first-byte See https://blog.cloudflare.com/a-question-of-timing/ and https://curl.haxx.se/docs/manpage.html for an explanation of how the curl variables relate to the various stages of the transfer. ![Diagram showing what each of the curl variable timings refer to against a typical HTTP over TLS 1.2 connection](https://blog.cloudflare.com/content/images/2018/10/Screen-Shot-2018-10-16-at-14.51.29-1.png) To get a better approximation of devtool's TTFB, we consider the time without the connection overhead: `%{time_starttransfer} - %{time_appconnect}` Uses a dirty `eval` to do the ttfb arithmetic. Depends on `bc` and `column` commands. # TODO * [x] Show progress when more than one request (`-n 2` etc) option is set * [ ] Sort output by fastest TTFB when multiple URLs are supplied * [ ] Colour code the `TTFB:` figure in the standard response, according to the speed of the response.