These tools expose an API, so you can call them from your own code rather than working through their interface. This is the list to start from if you are building AI into a product, a script or an automation.
Google Agent Engine provides AI-assisted capabilities for developers, AI engineers, or software teams.
Paid
API
Hypotenuse AI helps writers turn product information, topic, keywords, brand context, or source copy into prod...
Paid
API
Kahoot! provides game-based learning platform with AI-assisted question creation and live classroom quizzes fo...
Freemium
Free plan API
Kling AI helps creators generate, edit, or enhance images for practical design and visual-content tasks.
Freemium
Free plan API
LALAL.AI provides stem separation for creators, businesses, educators, and developers who need practical audio...
Freemium
Free plan API
Letta provides AI-assisted capabilities for modern software development workflows.
Paid
API
New Relic helps developers observability platform for monitoring applications, infrastructure, logs, traces, a...
Freemium
Free plan API
Notion AI helps writers turn Notion pages, notes, prompts, and workspace context into drafts, summaries, rewri...
Freemium
Free plan API
ParagraphAI helps writers turn prompt, selected text, or a message you are composing into emails, messages, pa...
Freemium
Free plan API
AI email management service that sorts lower-priority messages and reduces inbox clutter in existing mail acco...
Paid
API
SEO platform for rank tracking, keyword research, site audits, competitor analysis and content optimization.
Paid
API
SillyTavern provides conversational AI assistance for users who want interactive answers, follow-ups and task-...
Freemium
Free plan API
Squarespace Blueprint AI provides AI-assisted capabilities for modern software or AI workflows.
Paid
API
Sudowrite helps writers turn story ideas, scenes, characters, and existing prose into scene drafts, alternativ...
Paid
API
Temporal helps developers durable workflow platform for building reliable long-running application processes..
Freemium
Free plan API
Typeface helps writers turn brand guidance, campaign briefs, product information, and content inputs into mark...
Paid
API
Workplace collaboration suite with AI assistance for meetings, chat, summaries, and communication workflows.
Freemium
Free plan API
Ada Support provides conversational AI assistance for users who want interactive answers, follow-ups and task-...
Freemium
Free plan API
SEO platform for keyword research, backlink analysis, competitor research, content opportunities and AI-search...
Paid
API
AI-powered work management for teams handling projects, tasks, goals, workflows, and status updates.
Freemium
Free plan API
AssemblyAI provides speech API for creators, businesses, educators, and developers who need practical audio wo...
Paid
API
AI-powered code review and static analysis service designed to identify bugs, security issues, and maintainabi...
Paid
API
Cohere Command helps users with enterprise AI platform through an interactive AI chat experience.
Paid
API
CrushOn.AI provides conversational AI assistance for users who want interactive answers, follow-ups and task-f...
Freemium
Free plan API
What to check before you choose
Having an API is the start of the question rather than the end of it. Rate limits, pricing per call, whether there is a sandbox to develop against, and whether your inputs are retained or used for training all vary enormously, and all of them shape whether a tool is viable at scale. Official API documentation is the only reliable source for those details, and it changes often — treat this list as a way to find the candidates, then verify the specifics with the vendor before you build.
