Links

Books, sites and tools with a lot of knowledge in them, or one thing I keep needing to look up.

Learn

The Art of Electronics, 3rd edition: Horowitz and Hill: the electronics textbook.
Wampler's Guitar Pedal Course: A paid course on how pedal circuits work.
Electrosmash: Stage-by-stage analyses of classic pedal circuits. The site was not answering when this was written, so the link goes to an archived copy.
GEOFEX: R.G. Keen's articles: the technology of the Fuzz Face, the Tube Screamer and much more.
AMZ (muzique.com): Jack Orman's lab notebook and articles.
Vero P2P (Guitar Related Ramblings): Hundreds of stripboard, point-to-point, tag board and turret layouts of vintage and boutique fuzzes and drives, with schematics, amp work and value tables.
Tone Bender MkIII component values: A deep dive from the same blog: a table of the values used in MkIII and MkIV Tone Benders across makers and production runs, compiled from gut shots, with frequency plots of what the emitter cap and the bias resistors change.
The Big Muff π Page: Kit Rae's history of every Big Muff version, USA and Russian, with photos and specs, plus a guide to the circuit, wiring diagrams, mods and the clones: the reference for any Big Muff based build.

Mod Electronics (MOD Kits DIY): Complete pedal kits rated by build difficulty, most wired point to point on terminal strips, with full instructions and schematics. Sold through Amplified Parts; the kits are also in the library here.

DIY Stompboxes: The long-running forum.
PedalPCB Forum: Build reports and troubleshooting, for more than PedalPCB boards.
r/diypedals: Reddit.

Resistor color code decoder: For 5-band resistors.
Huntington Audio Labs: A one-person workshop and shop for breadboarding: pot, trimmer and switch breakouts, test jigs, and explorer board kits for learning how a fuzz or a common-emitter stage works. It also runs the reference site the next link is on.
Semiconductor company logos: Who made the chip, from the logo printed on it.
What Can I Build?: Enter the parts you have and see which circuits they cover: another take on the What can I build page here, with its own set of circuits.
Stompbox Layout: Create drill templates and see an enclosure layout before you drill. It also sells an STL file of any template you make.

Sightings: A free companion app for the Peak Atlas DCA75 semiconductor analyzer: identify parts, sweep curves, measure leakage, sort parts into bins and match them to pedal circuits. macOS, Linux and Android. The link opens its wiki: installation, first steps, curves, parts and bins, troubleshooting.
Sightings downloads: Ready-made builds for each platform.
Tayda UV Artwork Processor: Turns your enclosure artwork into the PDF that Tayda's UV printing service needs: pick the enclosure and the image for each side, and it checks the sizes and writes the file. Runs in a terminal or from the command line. The link opens its wiki: installation, preparing artwork, artboard sizes for every enclosure, white and gloss, troubleshooting.
Tayda UV Artwork Processor downloads: Builds for macOS, Linux and Windows.

JLCPCB assembly guide: z2amiller's notes on ordering assembled pedal boards.
JLCPCB component catalog: A searchable catalog of the parts JLCPCB can place.

The Workbench is one builder's notes, from Cryptid Effects: what I buy, where and why. The rest of Akashic is reference; this part is opinion.