Image credits and software notices
Openverse
Made using Openverse. Not endorsed or certified by Openverse.
Made using the Openverse API; Biro is not endorsed or certified by Openverse. Openverse is a discovery service, not a grant of rights. Biro checks provider records and URL consistency for CC0, Public Domain Mark, or CC BY metadata, but does not independently clear rights. Users should verify the linked source before use; licences and other rights can change or be inaccurate.
Each retrieved image carries its creator, source page and licence links on the board. Those credits remain with saved and exported boards.
Curated Bioicons illustrations
The bundled scientific illustrations listed in BIOICONS_ASSETS come from Bioicons revision d29e766ea7580b8063c4f47b29e872db40a4d979. Each selected file is in Bioicons' cc-0 directory and is distributed under CC0 1.0. Bioicons requires users to check each icon's individual licence.
Pinned upstream revision: d29e766ea7580b8063c4f47b29e872db40a4d979
- Bacterium by Pauline Franz — CC0 1.0
- Cell by Marnie-Maddock — CC0 1.0
- Mitochondrion by jaiganesh — CC0 1.0
- Plant leaf by Gina Vong — CC0 1.0
- Red blood cell by EwaOz — CC0 1.0
No asset catalogue or search result is a blanket warranty of copyright, trademark, privacy, publicity, or other rights. Source and licence links are retained with every picture so the applicable terms can be reviewed.
Reference pictures (anatomy, histology and structures)
Open-licence pictures reviewed for teaching, with Biro's labels and arrows drawn on top. Each carries its source, author, licence and changes on the board.
- Heart, opened from the front by Servier Medical Art (Servier Medical Art) — CC BY 4.0; zoom-in inset cropped off and its callout erased; labels added
- Nephron and its blood supply by Servier Medical Art (Servier Medical Art) — CC BY 4.0; labels added
- Neuron (motor neuron with a myelinated axon) by Servier Medical Art (Servier Medical Art) — CC BY 4.0; scaled; labels added
- Skin in cross-section: its layers by Servier Medical Art (Servier Medical Art) — CC BY 4.0; labels added
- Male reproductive system, from the front by Servier Medical Art (Servier Medical Art) — CC BY 4.0; scaled; labels added
- White blood cells: the five kinds by BruceBlaus (Blausen Medical) (Wikimedia Commons) — CC BY 3.0; scaled; labels added (placed as the source's labelled version names each cell)
- Brachial plexus, right side, from the front by Mattopaedia; derivative work: Captain-n00dle, MissMJ (Wikimedia Commons) — Public domain; the source's own label layer removed (its leader lines give each nerve's point); rendered to PNG; labels added
- Skin in cross-section: hair follicle, glands, receptors and vessels by Servier Medical Art (Servier Medical Art) — CC BY 4.0; scaled; labels added
- Heart valves seen from above (base of the heart, atria removed) by Servier Medical Art (Servier Medical Art) — CC BY 4.0; labels added
- Kidneys in coronal section, with the aorta and inferior vena cava by Servier Medical Art (Servier Medical Art) — CC BY 4.0; labels added
- Lungs and airways in the chest, from the front by Servier Medical Art (Servier Medical Art) — CC BY 4.0; scaled; labels added
- Alveoli at the end of a bronchiole, with their capillaries by Servier Medical Art (Servier Medical Art) — CC BY 4.0; labels added
- Liver lobule: a wedge from the central vein to the portal triad by Servier Medical Art (Servier Medical Art) — CC BY 4.0; scaled; labels added
- Digestive system, from the pharynx to the anus by Servier Medical Art (Servier Medical Art) — CC BY 4.0; top of the head outline cropped off; scaled; labels added
- Brain from the side: the lobes of the cerebrum by Mysid (after Gray's Anatomy, fig. 728); pointer lines added by Was a bee (Wikimedia Commons) — Public domain; rendered to PNG; the source's four empty pointer lines erased; labels added
- Eye in section, from the side by Servier Medical Art (Servier Medical Art) — CC BY 4.0; labels added
- Ear in section: outer, middle and inner ear by Servier Medical Art (Servier Medical Art) — CC BY 4.0; scaled; labels added
- Sarcomere: thick and thin filaments, with myosin and actin close up by DataBase Center for Life Science (DBCLS) (Wikimedia Commons) — CC BY 4.0; Wikimedia's 1280 px rendering; the source's Z and M letters cropped off; scaled; labels added
- Animal cell and its organelles by Servier Medical Art (Servier Medical Art) — CC BY 3.0; the source's empty label leaders erased, margins trimmed, scaled; labels added
Fonts, sounds and pictures
The fonts Biro draws and writes with, the interface sounds, and the pictures on the home page. Each font's full licence ships beside it.
Excalifont by Excalidraw; Ján Filípek / DizajnDesign, from Virgil — SIL Open Font License 1.1OFL.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs. The Latin subset at the top of fonts/ is the same face, served as "Tutor Hand" on Home. The licence text is the one Excalidraw records for the face; the font file itself names no licence.
Virgil by Ellinor Rapp — SIL Open Font License 1.1OFL.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs.
Assistant by The Assistant Project Authors — SIL Open Font License 1.1OFL.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs.
Cascadia Code by Microsoft Corporation — SIL Open Font License 1.1OFL.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs.
Comic Shanns by Shannon Miwa, Jesus Gonzalez and others — MITLICENSE.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs. The licence text is the one embedded in the font file.
Arimo by The Arimo Project Authors (designed by Steve Matteson) — SIL Open Font License 1.1Arimo-OFL.txt
Served where Excalidraw asks for Liberation Sans (next.config.ts), in place of the GPL 2.0 Liberation Sans 1.05 the package ships. Arimo is metric-compatible with it, so board text measures the same. The Regular instance of Google Fonts' Arimo[wght].ttf (version 1.341), made with fontTools and unchanged otherwise. Google Fonts lists Arimo under the OFL; older releases were Apache 2.0.
Lilita One by Juan Montoreano — SIL Open Font License 1.1OFL.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs.
Nunito by The Nunito Project Authors — SIL Open Font License 1.1OFL.txt
Copied unchanged from the @excalidraw/excalidraw package by scripts/copy-excalidraw-fonts.mjs.
Geist and Geist Mono by The Geist Project Authors (Vercel) — SIL Open Font License 1.1Geist-OFL.txt
The app's text face, downloaded from Google Fonts at build time by next/font and served from our own domain.
Kalam by Indian Type Foundry — SIL Open Font License 1.1Kalam-OFL.txt
The landing page's handwriting, downloaded from Google Fonts at build time by next/font and served from our own domain.
Tool click (Immersive Control Button Click Sound) by denielcz on Pixabay — Pixabay Content License
Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Menu open and close (Menu Beep Accept Soft) by Liecio (pixabay.com/users/liecio-3298866) — Pixabay Content License
The close is the same recording with its two notes swapped and pitched down. Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Question sent (Menu Beep Aqua Ploc) by Liecio (pixabay.com/users/liecio-3298866) — Pixabay Content License
Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Board changed (Menu Beep Short Tone) by Liecio (pixabay.com/users/liecio-3298866) — Pixabay Content License
Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Answer done (Menu Beep Simple Ping) by Liecio (pixabay.com/users/liecio-3298866) — Pixabay Content License
Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Something failed (Menu Beep Accept Soft B) by Liecio (pixabay.com/users/liecio-3298866) — Pixabay Content License
Slowed and dulled. Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Sidebar nav (Menu Beep Short Tone B) by Liecio (pixabay.com/users/liecio-3298866) — Pixabay Content License
Liecio has two uploads with this title (533775 and 533768); the download log names this one "Short_tone_B", so 533775 is the likely source. Free for commercial use without attribution; may not be sold or redistributed on its own as a sound file.
Hero video and poster by Biro — Biro's own output
A headless screen capture of Biro answering "Why do we have seasons?" (scripts/launch-capture.mjs), sped up 3x; the poster is a late frame. What it shows is drawn with the fonts above.
Landing examples by Biro — Biro's own output
Crops of real boards Biro drew: the seasons one from the launch capture, the others from eval screenshots.
Voice lab samples by Microsoft Azure AI Speech, requested by scripts/voice-samples.mjs — Azure AI Speech output under Biro's Azure subscription; the terms were not reviewed here
Three sentences in en-US-AvaMultilingualNeural and its HD voice, for the /voice-lab test page.
Chart and graph libraries
Charts use Vega-Lite and Vega under BSD-3-Clause. The graph explorer uses JSXGraph under its MIT licence option. Full, unmodified upstream licence notices for these libraries and their runtime dependencies are retained below.
- @types/estree 1.0.9 — MITLICENSE
- @types/geojson 7946.0.16 — MITLICENSE
- ansi-regex 6.3.0 — MITlicense
- ansi-styles 6.2.3 — MITlicense
- cliui 9.0.1 — ISCLICENSE.txt
- commander 7.2.0 — MITLICENSE
- commander 2.20.3 — MITLICENSE
- d3-array 3.2.4 — ISCLICENSE
- d3-color 3.1.0 — ISCLICENSE
- d3-delaunay 6.0.4 — ISCLICENSE
- d3-dispatch 3.0.1 — ISCLICENSE
- d3-dsv 3.0.1 — ISCLICENSE
- d3-ease 3.0.1 — BSD-3-ClauseLICENSE
- d3-force 3.0.0 — ISCLICENSE
- d3-format 3.1.2 — ISCLICENSE
- d3-geo 3.1.1 — ISCLICENSE
- d3-geo-projection 4.0.0 — ISCLICENSE
- d3-hierarchy 3.1.2 — ISCLICENSE
- d3-interpolate 3.0.1 — ISCLICENSE
- d3-path 3.1.0 — ISCLICENSE
- d3-quadtree 3.0.1 — ISCLICENSE
- d3-scale 4.0.2 — ISCLICENSE
- d3-scale-chromatic 3.1.0 — ISCLICENSE
- d3-shape 3.2.0 — ISCLICENSE
- d3-time 3.1.0 — ISCLICENSE
- d3-time-format 4.1.0 — ISCLICENSE
- d3-timer 3.0.1 — ISCLICENSE
- delaunator 5.1.0 — ISCLICENSE
- emoji-regex 10.6.0 — MITLICENSE-MIT.txt
- escalade 3.2.0 — MITlicense
- get-caller-file 2.0.5 — ISCLICENSE.md
- get-east-asian-width 1.7.0 — MITlicense
- iconv-lite 0.6.3 — MITLICENSE
- internmap 2.0.3 — ISCLICENSE
- json-stringify-pretty-compact 4.0.0 — MITLICENSE
- jsxgraph 1.13.3 — MITLICENSE.MIT
- robust-predicates 3.0.3 — UnlicenseLICENSE
- rw 1.3.3 — BSD-3-ClauseLICENSE
- safer-buffer 2.1.2 — MITLICENSE
- string-width 7.2.0 — MITlicense
- strip-ansi 7.2.0 — MITlicense
- topojson-client 3.1.0 — ISCLICENSE
- tslib 2.8.1 — 0BSDLICENSE.txt
- vega 6.4.0 — BSD-3-ClauseLICENSE
- vega-canvas 2.0.0 — BSD-3-ClauseLICENSE
- vega-crossfilter 5.1.3 — BSD-3-ClauseLICENSE
- vega-dataflow 6.1.3 — BSD-3-ClauseLICENSE
- vega-encode 5.2.2 — BSD-3-ClauseLICENSE
- vega-event-selector 4.0.0 — BSD-3-ClauseLICENSE
- vega-expression 6.2.2 — BSD-3-ClauseLICENSE
- vega-expression 6.1.0 — BSD-3-ClauseLICENSE
- vega-force 5.1.3 — BSD-3-ClauseLICENSE
- vega-format 2.1.3 — BSD-3-ClauseLICENSE
- vega-functions 6.2.0 — BSD-3-ClauseLICENSE
- vega-geo 5.1.3 — BSD-3-ClauseLICENSE
- vega-hierarchy 5.1.3 — BSD-3-ClauseLICENSE
- vega-label 2.1.3 — BSD-3-ClauseLICENSE
- vega-lite 6.4.3 — BSD-3-ClauseLICENSE
- vega-loader 5.1.3 — BSD-3-ClauseLICENSE
- vega-parser 7.1.3 — BSD-3-ClauseLICENSE
- vega-projection 2.1.3 — BSD-3-ClauseLICENSE
- vega-regression 2.1.3 — BSD-3-ClauseLICENSE
- vega-runtime 7.1.3 — BSD-3-ClauseLICENSE
- vega-scale 8.1.3 — BSD-3-ClauseLICENSE
- vega-scenegraph 5.3.0 — BSD-3-ClauseLICENSE
- vega-selections 6.1.5 — BSD-3-ClauseLICENSE
- vega-statistics 2.0.0 — BSD-3-ClauseLICENSE
- vega-time 3.3.0 — BSD-3-ClauseLICENSE
- vega-transforms 5.2.2 — BSD-3-ClauseLICENSE
- vega-typings 2.3.0 — BSD-3-ClauseLICENSE
- vega-util 2.1.3 — BSD-3-ClauseLICENSE
- vega-view 6.2.0 — BSD-3-ClauseLICENSE
- vega-view-transforms 5.2.2 — BSD-3-ClauseLICENSE
- vega-voronoi 5.1.3 — BSD-3-ClauseLICENSE
- vega-wordcloud 5.1.3 — BSD-3-ClauseLICENSE
- wrap-ansi 9.0.2 — MITlicense
- y18n 5.0.8 — ISCLICENSE
- yargs 18.0.0 — MITLICENSE
- yargs-parser 22.0.0 — ISCLICENSE.txt