PromptAncestry vs Prompt Assay
Both are self-serve prompt workbenches for individuals — free tier, no card, no demo call. The biggest difference: PromptAncestry includes AI usage in your plan; Prompt Assay has you bring your own provider key.
Prompt Assay sources checked October 28, 2026. Features and prices may change; this is not an endorsement by Prompt Assay.
When PromptAncestry fits
You don't want to manage API keys or a provider bill. You want to analyze a prompt, get three candidate revisions, keep each version's parent and locked preferences, run your own test cases, and review AI-judge opinions separately from your own scores before choosing what to keep.
When Prompt Assay fits
You already have Anthropic, OpenAI or Google keys and want unlimited calls on them, Agent Skills authoring, multi-provider behavioral evals, a REST API and SDK, or a shared team library. It's built for prompt engineers shipping to production.
What the prices include
PromptAncestry Pro: $11.99/month
One account, 25 optimizations and 6 AI-judged test runs per month, AI usage included. Free: 3 optimizations and 1 judged run. No provider key, no overage charges; 30-day money-back guarantee.
Prompt Assay Solo: $49/month + your provider bill
Unlimited AI calls on your own keys, full version history, evaluation suites with regression. Free: 250 AI calls a month on your key and a 7-day version view. Team is $99/seat/month (3-seat minimum).
Questions before choosing
Do I need my own AI provider API key?
Not with PromptAncestry — AI usage is included in each plan's monthly allowance, so there is no separate provider bill. Prompt Assay is BYOK (bring your own key) on every tier, including Free, after 7 platform-funded starter calls; inference is billed by your provider with no markup.
Which is cheaper for one person?
PromptAncestry Pro is $11.99/month with 25 optimizations and 6 AI-judged runs included. Prompt Assay Solo is $49/month with unlimited AI calls on your own keys, plus whatever your provider charges. Heavy users with their own keys may prefer unlimited calls; light users may prefer included usage.
Do either require a demo call or credit card?
No. Both offer a free tier without a card and are self-serve. Prompt Assay asks you to contact them only for SSO, BAA or DPA needs.
Does an AI score prove a prompt is better?
No. In PromptAncestry, AI-judge scores are subjective signals, shown separately from your manual scores and measured data. You decide which version to promote.