How this board is built, tested and sourced

What the page is made of

Pedals is nineteen static pages on labs.llc and 5 scripts of its own, with the pitch detector it shares with the labs.llc Tuner. There is nothing behind the board doing anything: no account, no database, no upload. The audio runs in your browser’s Web Audio engine. 9 of the 15 effects are graphs of the engine’s standard nodes, 5 are AudioWorklet processors, which the Web Audio specification describes as scripts that “process audio on the rendering thread”, and the wah is a standard filter moved by one. Each effect’s page draws its graph.

A pedal that is switched off is not in the graph. The chain is rebuilt every time a switch is pressed or a pedal is moved: everything is unplugged, and then the pedals that are on are connected in order. That is what “true bypass” means on this board, and it is why a bypassed pedal can be shown to change nothing at all.

The 3 test signals are computed when you first press Start. The plucked string and the chord use the Karplus–Strong method: a delay line one period long is filled with noise and fed back through a two-sample average, so that the top of the sound dies first, as a string’s does. The sustained note is twelve harmonics added together.

How the effects were tested

The browser can run an audio graph without playing it, as fast as it can compute, and hand back the samples: an OfflineAudioContext. Each effect was built in one, by the same code the page uses, given a signal whose properties are known (a single impulse, a pure tone, seeded noise) and rendered. The output was then measured, and the measurement compared with what the effect’s page says it does. The sentences on each effect’s page are the test’s own output, with the numbers it found.

The first test for every pedal is bypass: switched off, the rendered output must equal the input in every sample, exactly, not approximately.

The tests were first run on 2026-09-28 16:45 UTC for pedals.llc, in Chrome/154.0.8037.58. When the board moved to labs.llc they were run again on the files labs.llc serves, in Chrome/154.0.8037.58: 73 of 73 sentences came out word for word the same.

What the tests do not cover: how anything sounds, which is for ears; how the effects behave in browsers other than the one named above; and the latency of any real device. No real instrument, audio interface or phone was tested.

What stays in your browser

• Your sound. Audio from your input goes into the audio graph and out to your output device. It is not recorded, stored or sent anywhere. The only request the board’s own scripts make is for their AudioWorklet module, a file on labs.llc.
• The input permission. The input is requested only when you press Start with “Your instrument” chosen, and released when you press Stop or leave the page. It is not released when you switch to another tab, because people play along to something in another tab; the browser’s own recording indicator stays lit for as long as the page holds the input.
• Your board and presets. The board as you left it, your saved presets and the output volume are kept in this browser’s local storage under the names pd_board, pd_presets and pd_volume. The paper or dark edition you chose is kept under labs_edition, in local storage and in a cookie (and under labs.mode, an older name labs.llc keeps in step). Clearing the site’s data in your browser removes them all. Presets saved on pedals.llc before the board moved here stay in that site’s storage: a browser keeps each site’s storage apart, so this page cannot read them. A share link made there still opens here.
• Share links. The board is encoded in the fragment of the link, the part after the #. RFC 9110 says fragment identifiers “are not sent in requests”, and warns that they are visible to scripts on the page. So when a link is opened, this page reads the board and then removes the fragment from the address bar. The analytics tag in the head of the page starts before that, as the next point says.
• Analytics. labs.llc counts visits with Google Analytics, the one script on the page that talks to anyone else, and only from labs.llc itself. It is told which page was opened and in which edition, and, as on every labs.llc tool, that one of the page’s controls was first used, that the page was in use for thirty seconds, and how quickly the page drew and answered: its LCP, CLS and INP timings, sent as one web_vital event with the tag and the id or class of the element involved (never its text), the edition, the path and a random id for that one page load. The board’s own scripts tell it nothing: not the audio, not the knob settings, not the presets. Because the tag starts before the board reads a share link, the address it is given for the page view can still carry the #b= code. That code is the board’s settings (which pedals, in what order, where the knobs are) and nothing about you.
• The rest of the page. The menus, the search and the Lab Assistant around the board are labs.llc’s own and load the site’s own files; the assistant sends what you type into it to labs.llc only when you ask it something. The site’s legal page has the privacy note for all of labs.llc.

What this board does not claim

No pedal here is a model of a product, is named after one, or is said to sound like one. The cabinet is a filter curve and an approximation. The reverb is generated noise, not a room. The octave pedal follows one note and its page shows what it does with two.