One API key, one endpoint — access to modern AI models

Thelsy is an API gateway service. We provide software developers, indie builders and small teams with programmatic access to large language models through a single, OpenAI-compatible endpoint. Point your existing SDK at our base URL and start building — no infrastructure to run, no provider accounts to manage, no token-by-token bookkeeping to write yourself.

What the service is

OpenAI-compatible API

Standard /v1/chat/completions interface. Works with official OpenAI SDKs and common third-party clients by changing only the base URL.

Token-based usage, monthly plans

Subscribe to a monthly plan that includes a token allowance. Usage beyond the allowance is billed per million tokens at the overage rate shown below.

Usage dashboard & API keys

Create and revoke your own API keys, set per-key limits, and monitor consumption and spend in your account dashboard.

Vision input supported

The model we serve accepts text and image input (image understanding). It does not generate images.

Base URL

https://api.thelsy.com/v1

Example request:

curl https://api.thelsy.com/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"deepseek-flash","messages":[{"role":"user","content":"Hello"}]}'

Pricing

All plans are billed monthly in US dollars. Included allowance is measured in tokens (one million tokens = 1M tokens). Cancel any time; plans renew until cancelled.

Plan	Monthly price	Included usage	Overage
Starter	$19 / month	30M tokens	$0.80 / 1M tokens
Pro	$49 / month	80M tokens	$0.80 / 1M tokens
Business	$149 / month	250M tokens	$0.75 / 1M tokens

Off-peak pricing benefit: our upstream model provider charges reduced rates during off-peak hours. Workloads scheduled outside peak hours are served at the same plan price, which makes off-peak batch jobs significantly more economical.

Plans are sold through our payment platform, which acts as the merchant of record and handles applicable taxes, invoices and card processing. See Refund Policy for cancellation and refund terms.

How it works

Choose a plan and complete checkout on our payment platform.
You receive access to your account, where you create one or more API keys.
Call https://api.thelsy.com/v1 from your application with your key.
Track token usage and spend in your dashboard.

Who it is for

Developers building chat, summarisation, extraction or analysis features into their products
Small SaaS teams that want one API key instead of multiple provider accounts
Agencies and freelancers who need reliable throughput for client projects

Capability boundaries

Supported: text generation and conversation; image understanding (image input).
Not supported: image generation; audio/video generation; results are produced by the upstream model provider and may be inaccurate — verify important output.

Acceptable use

This is an API access service for lawful software development. You may not use it to generate illegal content, to deceive or defraud, to send spam, to infringe intellectual property, to violate privacy, or to attempt to bypass model safety systems. A full list of prohibited uses and the terms governing the service are in our Terms of Service.

Contact

Questions before subscribing, or need help after? Email 393516700@qq.com. We usually reply within one business day.