Claude Projects vs. ChatGPT custom instructions: pick one
The coffee shop on Lexington has its regulars sorted by drink before they reach the counter — muscle memory built over hundreds of orders. Your AI should work the same way, but most operators are teaching it the hard way, every single time.
Claude Projects vs. ChatGPT custom instructions: which one fits your workflow
Both let you skip the context-setting preamble, but they’re built for different types of work.
ChatGPT custom instructions live globally across every chat. You write once—up to 1,500 characters about your business, voice, audience, and defaults—and ChatGPT applies it everywhere. It’s brilliant if you’re a solo operator who uses AI for the same handful of tasks: drafting social posts, rewriting email subject lines, summarising reader feedback. You set your tone (“casual, no jargon”), your audience (“newsletter operators, 500-5,000 subscribers”), and your output preferences (“always include character counts for subject lines”), and you’re done. The limitation: it’s one-size-fits-all. If you’re working on sponsor outreach in one tab and SEO meta descriptions in another, the same instructions apply to both.
Claude Projects compartmentalise. Each Project holds up to 200,000 words of context—brand guidelines, past campaign data, reader survey responses, even entire Substack exports—and you pick which Project to work inside. You might have one for email copy (seeded with your best-performing subject lines and your welcome sequence), another for longform articles (loaded with style notes and keyword targets), and a third for sponsor decks (with past pitch templates and conversion data). The cost: Projects live only on Claude Pro ($20/month) or Claude Team ($30/user/month). Custom instructions on ChatGPT are free on all tiers, including the $20/month Plus plan.
The deciding question: do you need one persistent voice, or do you switch contexts multiple times a day? If it’s the former, custom instructions are faster to set up and free to maintain. If it’s the latter—especially if you’re managing client work, multiple brands, or distinct content types—Projects pay for themselves in the time you’d otherwise spend re-explaining context. The full breakdown, with setup walkthroughs and sample instructions for newsletter operators, is on the site.
TACTIC
The five-sentence AI brief that saves you fifteen minutes per session
Whether you use Projects or custom instructions, front-load five facts: your newsletter’s niche, subscriber count, monetisation model, tone, and the one thing you never want the AI to do. Example: “I run a weekly design newsletter for 8,000 product managers. Monetised via sponsorships, $400 CPM. Tone is direct, no buzzwords. Never use emoji or exclamation marks.” That’s 37 words. It eliminates 90% of the back-and-forth in every session, and it stops the AI from hallucinating a chirpy brand voice you’d never use. If you’re on ChatGPT, this goes straight into custom instructions. If you’re on Claude, save it as the first document in every new Project.
TOOL WATCH
Perplexity now lets you set persistent instructions too
Perplexity rolled out custom instructions last month for Pro subscribers ($20/month). It’s the same concept as ChatGPT’s: one global context block that follows you across searches. The difference: Perplexity’s strength is research, not writing, so the instructions are better suited to refining how it surfaces sources and formats citations. If you’re using Perplexity to pull competitor analysis, track SEO trends, or gather data for sponsor decks, you can now tell it to prioritise recent sources, skip Reddit threads, or always include publication dates. It won’t replace Projects for deep content work, but for research sessions it’s faster than re-typing “only show results from the last six months” every time.
READER QUESTION
Can you export a Claude Project and reuse it elsewhere?
Not natively. Projects live inside Claude’s interface, and there’s no “export Project” button. But you can copy the knowledge base manually: open the Project, grab the documents you uploaded, and paste them into a new Project or into a ChatGPT custom instruction block (if you’re under 1,500 characters). If you’ve built a working Project and want a backup or want to mirror it for a colleague, the fastest route is to save the source files—Google Docs, Notion exports, CSV data—in a shared folder and rebuild from those. It’s clunky, but it’s the only option until Anthropic ships Project templates or export functionality. One workaround: if you’re on Claude Team, you can share Projects with team members directly.
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