APL logo
As of November 2024, APL does not have a logo like many other programming languages do. After a consensus at their September 9th 2021 webinar, BAA will head an effort to adopt a universal vendor-agnostic logo for APL. This article collects draft proposals for the universal APL logo. Feel free to add your own.
To leave feedback on or ideas for the existing proposals, see the Discussion page.
For reference, the logos of a selection of other programming languages are illustrated here.
Logos based on apples
50 Years Apple
This is based on the logo that Dyalog Ltd. commissioned for APL's 50th anniversary, which was inspired by the original "I like APL" apple motif; the green colour also recognises this original motif. As with some of the other suggestions, the simplicity and single colour means that it would still work well when shrunk to the size of a favicon and could be rendered in black and white without loss of detail.
Angular Textured Apple
This apple-based logo is designed by Aaron Brudzewsky. It uses realistic textures exclusively, for a crisp fresh look. The angles and orthogonally constructed letters hint at APL's emphasis on orthogonal arrays.
Cube Apple
This is a cube, which is a common APL motif, e.g. used for APL2 (including the book APL2 at a glance), APL*PLUS and Dyalog APL. However, one quarter has been modified to resemble a leaf, thus making the cube into an apple, another common association with APL. The leaf is supposed to hint at the Del which symbolises function definition and has been used in application icons for APL+ and APLX. The green colours come from IBM's modern Carbon design to honour IBM's role APL's history. The lettering spells out "APL" while also hinting at APL's usage of special glyphs; here ⍝⍴⌊ which look very close to the forms found in the widespread APL385 Unicode font.
Nested Bitmaps
This logo is a reinterpretation based on the classic APL apple with the leaf styled as a filled Del which symbolises function definition and has been used in application icons for APL+ and APLX. The green colour comes from IBM's modern Carbon design to honour IBM's role APL's history. The apple is subdivided into a rectangular pattern which is supposed to invoke a matrix and the middle row in turn holds three 4-row, 3-column Boolean matrices to spell out "APL" as bitmaps. This matrix of matrices hints at APL's multi-dimensional nested arrays. The logo exists in various variations, and each comes has a version for light backgrounds and one for dark backgrounds.
Script apple 
This apple logo is a basic update of IBM's classic "I like APL" promotional, but with the leaf styled as a filled Del which symbolises function definition and has been used in application icons for APL+ and APLX. The colours comes from IBM's modern Carbon design to honour IBM's role APL's history. The script lettering commemorates APL's origins as handwritten notation and at the same time symbolises the ease with which APL is written. On dark backgrounds, the lettering would be produced in white rather than black. The logo also exists as a filled green version.
Logos based on grids
APL Matrix 
This logo is inspired by the logos of TypeScript, JavaScript, and WebAssembly, being lettering along the bottom of a theme coloured square. The APL logo is distinct in its usage of Lamp Rho Downstile and in splitting up the square into subsquares to hint at APL's multi-dimensional arrays. The colour of the centre square is from IBM's Carbon design and occupies the saturated green gap in the rainbow of programming language logos. For small icons, the lettering can be left out. As an alternative to the Lamp Rho Downstile, the letters could be shown in a proper font like the traditional IBM user guide cover sheet font Clarendon (as used in the Fortran logo), or the modern IBM programming font Plex Mono.
APL Rotated Array 
Following the central ideas of "Array-Based" Language, the three letters of the name, and the most established APL logo to date (the APL Wiki one); This logo tries to encompass and simplify all of them, while the rotation and the negative space hints the nature of the multi-dimensional arrays that APL is founded on. The colour is green, hinting the IBM Carbon green lettering, begin friendly with hard reproduce surfaces that will need a black-and-white version, and also becoming the only green logo in the programming language landscape. Also exists in a darker version. Made by OOQQ
APL Wiki
The APL Wiki logo encapsulates features of APL, is visually striking and takes an interesting new approach over traditional apple or cube designs. Its use here has already established its independent, community-wide use. It works in a variety of sizes and its simple black and white palette makes it suitable for all media forms. It could be enhanced with the letters A P L either underneath, or within the middle dots of the middle row.
Clearly, if you visit the APL wiki you'd expect to see the APL logo - and perhaps you already do.
APL Wiki Revised 
This is a variant of the APL Wiki logo that combines many traits from other suggested logos such as the green colour from
IBM's modern Carbon design and the Lamp Rho Downstile ⍝⍴⌊ glyphs displayed in the center.
Logos based on the letters APL
APL Array
This logo represents an array and the letters A, P, and L, which together make up the array.
APL Germany
The icon used by APL Germany.
Direction and Magnitude
The colors are taken from the Canadian flag.
Display matrix
This is the output from the classic DISPLAY function when applied to the matrix 1 3⍴APL.
Ligatures
This is Jon McGrew's reworks of an original design by Joseph DeKerf that used the ITC Avant Garde font. The original is arguably ambiguously APL/ALP, hence the alternative versions.
Parallel Lines
This logo is from the cover of the original edition of Paul Berry's SHARP APL Reference Manual.
Plain Ellipse
This is a plain ellipse designed by Juda Brudzewsky. It is similar to the logo of PHP, using the warning red from IBM's Carbon design. The font is reminiscent of Clarendon used for the covers of IBM's manuals at the time when APL first appeared. Note that APL\360's name was originally always styled in italics, technology permitted.
Logos based on APL glyphs
3D Lamp Rho Downstile
This is a variation on the APL Germany icon, created by Tobias Wessels after Dieter Kilsch proposed it during the APL Germany meetup in November 2021. It takes the idea of using ⍝⍴⌊ as stylised letters "APL" and combining them into a 3D structure, alluding to APL's multi-dimensional arrays. It should be noted that it is intended as a rough draft, and that both final design and colour choices are subjust to evaluation by a professional logo designer.
Lamp Rho Downstile
IBM Carbon green lettering of "APL" stylised as APL's glyphs ⍝⍴⌊ in a manner that is very close to the forms found in the widespread APL385 Unicode font.
Quad APL
This is the design by LdBeth that plotted by the MetaPost program below. It is composed visually by Quad, And, Circle (Pi), Left Tack, and forms the stylized "APL". One day he needs an icon for his APL keyboard layout, and he spent an hour to do the sketching and wrote the code in his favorite font design tool MetaFont. The right one is the old, original one. There might be alternative glyphs, and he will gladly accept any interesting suggestions for improvements.
% show bound box prologues := 2; beginfig(1); % edge e=5; a=40;b=28; % misc points m=0.3a;n=0.5b;t=2; % center z0=(e+n,e+0.4a);r=7; % quad z1=(e,e);z2=(e,a+e);z3=(b+e,a+e);z4=(b+e,e); % and z5=(e+t,e+m);z6=(e+n,e+0.8a);z7=(e+b-t,e+m); % pi z8=z0+(0,r);z9=z0+(r,0); z10=z0-(0,r);z11=z0-(r,0); % left z12=(z1+z4)/2;z13=z10-(0.3b,0); % draw pickup pencircle scaled 3; draw z1--z2--z3--z4--cycle; draw z5--z6--z7; draw z8..z9..z10..z11..cycle; draw z0--z12; draw z10--z13; endfig; end