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Prompt Assay

promptassay.ai

From $49/mo WebAPI
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Spec score 7.7 #17 of 26 in Prompt Management Software

What it is

Prompt Assay is a web and API workbench for authoring, refining, versioning, testing, and shipping LLM prompts and Agent Skills. Its critique feature evaluates clarity, completeness, structure, technique use, robustness, and efficiency, with written reasons. An in-editor AI pair can brainstorm, critique, improve, rewrite, compare, and convert content. Connect your own Anthropic, OpenAI, or Google models to run a prompt across 2–5 models in parallel and compare outputs, latency, token use, and cost; optional LLM-as-Judge scoring is available. For Agent Skills, users can create multi-file bundles, critique them, and run Behavioral Evals across Claude, GPT, and Gemini. Imports accept Markdown, Anthropic JSON, OpenAI JSON, or raw text; its bundle preserves versions, tags, fragments, and metadata. The Free plan is free, with 250 calls monthly and one seat; seven initial platform-funded calls are available before BYOK is needed for ongoing use. Solo costs $49 a month and includes API and TypeScript SDK access. The public API and SDK require Solo or higher.

Spec sheet

Product
Prompt Assay is a workbench for authoring, refining, versioning, testing, and shipping LLM prompts and Agent Skills.Read 7 Oct 2026 · promptassay.ai
Intended users
The maker describes the product for prompt engineers, teams sharing prompt libraries, researchers evaluating models, and developers retrieving prompts through an API or SDK.Read 7 Oct 2026 · promptassay.ai
API
The public REST API and TypeScript SDK require Solo tier or higher; API requests are authenticated with an API key.Read 7 Oct 2026 · promptassay.ai
Maker
Jon Lasley founded Prompt Assay; the About page describes his enterprise technology and applied AI experience but does not state a founding year or headquarters.Read 7 Oct 2026 · promptassay.ai
Agent Skills
Users can author multi-file Agent Skill bundles, critique them, and run Behavioral Evals across Claude, GPT, and Gemini.Read 7 Oct 2026 · promptassay.ai
AI actions
The in-editor AI pair offers brainstorm, critique, improve, rewrite, compare, and convert actions.Read 7 Oct 2026 · promptassay.ai
Critique
Its prompt critique scores clarity, completeness, structure, technique usage, robustness, and efficiency, with written reasons.Read 7 Oct 2026 · promptassay.ai
Data retention
Provider responses are generally not retained server-side, with evaluation test outputs and Skills Behavioral Eval results as stated exceptions.Read 7 Oct 2026 · promptassay.ai
Free tier limit
Free includes 250 calls per month and one seat; seven initial platform-funded calls are available before BYOK is needed for ongoing use.Read 7 Oct 2026 · promptassay.ai
Imports and exports
Prompt imports support Markdown, Anthropic JSON, OpenAI JSON, and raw text; the Prompt Assay bundle preserves versions, tags, fragments, and metadata.Read 7 Oct 2026 · promptassay.ai
Key handling
Provider API keys are encrypted at rest, never appear in logs, and are used only for LLM calls the user triggers.Read 7 Oct 2026 · promptassay.ai
Model comparison
Users can run one prompt across 2–5 BYOK models in parallel and compare outputs, latency, tokens, and cost, with optional LLM-as-Judge scoring.Read 7 Oct 2026 · promptassay.ai
Model providers
The workbench supports BYOK connections to Anthropic, OpenAI, and Google models.Read 7 Oct 2026 · promptassay.ai
Training and certifications
Prompt Assay says it does not train on customer content and does not currently hold SOC 2 or ISO 27001 attestations.Read 7 Oct 2026 · promptassay.ai

Plans and prices

Solo $49 a month $49/ month Unlimited AI calls on your keys · full prompt and Skill version history · public REST API and TypeScript SDK · single seat Read 7 Oct 2026 · promptassay.ai
Team $99 a month $99/ seat / month; minimum 3 seats; annual billing available 3 to 15 seats · shared org library and evaluation suites · owner, admin, and member roles Read 7 Oct 2026 · promptassay.ai
Enterprise Priced on request Custom contract Unlimited seats · SAML SSO · custom tier controls · data processing agreement · priority support Read 7 Oct 2026 · promptassay.ai
Free Price not published $0/ month 7 platform-funded calls to start · 250 AI calls a month · single seat · 7-day version view · BYOK for ongoing use Read 7 Oct 2026 · promptassay.ai

Every Prompt Assay plan and price →

Strong points and limits

Strong points

  • Critiques prompts across six named dimensions, with reasons.
  • Compares outputs, latency, tokens, and cost across 2–5 models.
  • Supports multi-file Agent Skills and Behavioral Evals.
  • Imports Markdown, Anthropic JSON, OpenAI JSON, and raw text.

Limits

  • Free plan is limited to 250 calls monthly and one seat.
  • Ongoing Free-plan use requires BYOK after seven initial calls.
  • Public REST API and TypeScript SDK require Solo or higher.
  • No SOC 2 or ISO 27001 attestations currently.

Who it suits

It suits prompt engineers and teams managing shared prompt libraries, as well as researchers comparing models. Developers who need to retrieve prompts through an API or SDK need Solo or higher.

Verdict

Prompt Assay combines prompt editing, critique, versioning, model comparison, and Agent Skill evaluation in one workbench. The Free plan has a stated monthly call and seat limit, while API and SDK access starts at Solo for $49 a month.

Where Specifiction places it

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