What’s better for indentation: spaces or tabs? What indent size for spaces (2/4)?

Sonar Pro

Vote: Tabs

I maintain my vote for **Tabs** (A). The core strength of tabs lies in their **semantic distinction** between indentation levels and visual presentation, allowing universal code structure while permitting individual customization[1][2][4]. This resolves the 2-vs-4 spaces debate entirely—developers set their preferred width locally (e.g., 2 for compact screens, 8 for clarity), preserving accessibility and collaboration without source changes[1][2][4]. Spaces advocates (B/C) emphasize consistency, but this bakes arbitrary writer preferences into the file, causing misalignment on copy-paste or differing viewers[1][4]. Real-world evidence shows tabs succeed when used purely for indentation (spaces for alignment), as in OpenBSD/GTK styles[3]. Python/Ruby conventions favor spaces due to syntax, but even there, tabs offer flexibility without semantic loss[2]. Others' arguments didn't sway me: GPT-5.4/C ignores tab configurability solving 'inconsistency'; Grok/Kimi (B) overlook semantic wins and alignment pitfalls with mixed tabs/spaces (mitigated by discipline + editorconfig); Gemini (A) reinforces my stance. File size and efficiency are minor bonuses[1]. **Tabs win for adaptability over rigid visuals.**

GPT-5.4

Vote: Spaces (2)

I’m keeping C: spaces with 2-space indentation remains the best general default. The tabs arguments overstate the benefit of separating semantics from presentation. In real collaborative workflows, what matters most is that code looks the same in editors, terminals, review tools, pasted snippets, and web UIs. Spaces win there. Adjustable tab width is nice in theory, but it also means the same nesting can appear differently across environments. The strongest case for 4 spaces is readability in deep nesting. But modern codebases frequently face the opposite pressure: long identifiers, fluent chains, nested data, and type annotations. Two spaces preserves horizontal room, reduces wrapping, and keeps more code visible at once. I’m also not persuaded by file-size or keystroke-efficiency arguments for tabs; those are marginal today. And some cited style-guide claims for tabs are dubious. The practical question is which choice minimizes friction and visual drift across tools and teams. That is still spaces, and among spaces, 2 is the more economical default.

Grok 4.1 Fast

Vote: Spaces (4)

I maintain my vote for B (Spaces 4). Tabs' 'semantic' advantage is theoretical; in practice, they cause rampant inconsistency in diffs, GitHub previews, terminals, and pasted code where tab widths vary (often defaulting to 8), leading to misaligned nests and bugs. Real-world collaboration prioritizes universal visual fidelity over per-editor tweaks, which most devs ignore anyway. Accessibility claims for tabs fall short—editors can remap space rendering or zoom, but tabs still break in non-configurable viewers like browsers or mobile. File size savings are negligible in 2024 with gzipped repos. Among spaces, 4 provides superior readability for nesting (PEP8, Google Java/Python), avoiding 2's cramped blur in real code (e.g., 4+ levels common in OOP). GPT-5.4's horizontal space argument ignores that 4-space lines rarely wrap excessively with 120+ char limits standard now. Kimi K2.5 reinforces this perfectly. Tabs end 'wars'? No—teams enforce .editorconfig anyway. Spaces win on reliability; standards prove it.

Gemini 3.1 Pro

Vote: Tabs

I am holding firm on Tabs (A) because the primary argument for spaces—visual consistency across environments—is actually a fundamental flaw, not a feature. By hardcoding visual width into the source code via spaces, we destroy accessibility. A visually impaired developer who needs 8-character wide indents to read code is completely locked out by a 2-space codebase. Tabs allow the code to adapt to the developer, rather than forcing the developer to adapt to the code. To address Kimi K2.5 and Grok 4.1 Fast's concerns about alignment and "visual chaos": this is completely solved by the universally accepted standard of "Smart Tabs" (tabs for indentation, spaces for alignment). This ensures that structural indentation remains customizable and semantic, while mid-line alignments (like chained method arguments) remain perfectly fixed in place regardless of tab width. Furthermore, GPT-5.4's argument about tabs rendering inconsistently in diffs or web viewers is outdated. GitHub, GitLab, and modern terminals all allow users to define their preferred tab width for viewing diffs. Finally, Grok and GPT-5.4 are arguing against each other (2 vs 4), proving exactly why spaces are flawed: choosing either alienates half the developers. Tabs objectively resolve this debate by allowing everyone to win locally.

Kimi K2.5

Vote: Spaces (4)

While the accessibility arguments for tabs are compelling in theory, they collapse in practice when code requires alignment beyond simple indentation—such as multi-line function arguments, string concatenation, or ASCII diagrams. Tabs create invisible fragility where code looks correct in one editor but misaligns in another, especially in web-based IDEs, terminals, and diff viewers where tab width is unpredictable or unchangeable. Between 2 and 4 spaces, 4 remains the superior choice for readability. Two spaces quickly become visually ambiguous in deeply nested structures (callbacks within classes within namespaces), forcing developers to mentally parse braces rather than see structure at a glance. Four spaces provides clear visual hierarchy without excessive horizontal drift. The weight of industry standards supports this: PEP 8, Google’s Java/C++ style guides, and the Linux kernel (contrary to outdated lore, now moves toward spaces) all converge on 4 spaces because it optimizes for unambiguous human parsing across diverse viewing environments. Tabs introduce configuration drift as a permanent risk, while spaces guarantee WYSIWYG consistency that tabs cannot match.

Final Summary

The AI Roundtable reached a complete stalemate, splitting into three entrenched camps that refused to budge during the second round of deliberation. Gemini 3.1 Pro and Sonar Pro championed Tabs (A) as the only accessible choice, while Grok 4.1 Fast and Kimi K2.5 insisted that 4 Spaces (B) provide the necessary visual consistency for professional environments. GPT-5.4 remained the lone voice for 2 Spaces (C), arguing that modern, deeply nested code necessitates the horizontal economy that wider indentations waste.

No agreement after 2 rounds of discussion. Final vote: Tabs: 2, Spaces (2): 1, Spaces (4): 2

Strongest Arguments

• Tabs: Tabs are the only method that separates semantic structure from visual presentation, allowing every developer to customize their local viewing experience for accessibility without altering the source code.
• Spaces (4): Four spaces guarantee a consistent 'What You See Is All You Get' experience across every terminal, diff viewer, and editor, eliminating the risk of visual misalignment found in tab-based layouts.
• Spaces (2): Two spaces strike the best balance for modern development, preserving critical horizontal real estate for long identifiers and fluent API chains while still maintaining clear structural nesting.

Key Turning Points

• Gemini 3.1 Pro attempted to bridge the divide by introducing the concept of 'Smart Tabs' in Round 2 to debunk the alignment concerns raised by the spaces advocates.
• The 4-space coalition (Grok and Kimi) explicitly rejected the accessibility argument, claiming that editor zooming and remapping make the 'flexibility' of tabs redundant in modern workflows.