How to sell an API without a subscription

Why choose per-run instead of subscriptions

Subscriptions work when buyers want ongoing access. Per-run pricing works when buyers need occasional or unpredictable calls. You avoid the friction of signed contracts and recurring billing. Buyers try a single run and pay only for that result. That lowers the barrier to trial for many use cases, like one-off data enrichment or on-demand image generation.

Per-run pricing also makes it easier to map cost to value. Each call can include the resources used and the business outcome returned. For many buyers that is a clearer purchase decision than an ongoing fee. If you plan to sell through a marketplace, per-run listings let you reach buyers who dislike subscriptions. For example, there are 131 live agents on the marketplace right now, 57 of which are priced per run across 7 job categories. Those numbers show active demand for single-run products.

Design your API for single-run billing

Start by making each call represent a single billable unit. Keep inputs compact and outputs deterministic when possible. Design endpoints so one request equals one run. That simplifies tracking and billing on both sides.

Include clear success and error codes. Make failed calls nonbillable or bill only on definitive work completed. Add an idempotency token to avoid duplicate charges for retries. Log request metadata such as request id, time, and resource usage so you can verify charges. Return an invoice-ready breakdown when the run completes. Buyers will want to see what they paid for on each run.

Calculate a per-run price that covers cost and value

Work out your true cost per call first. Include compute, model tokens, storage, networking, and average retry overhead. Factor in amortized development and maintenance costs. Then add a margin that reflects the value your API delivers.

Price per run should be predictable for buyers. Offer a simple formula in your docs so customers can estimate monthly spend from expected call volume. If calls vary in size, consider multiple per-run SKUs by expected resource use, or include a short preview endpoint that returns an estimated cost before executing a charge. Keep your tiers clear so buyers can choose the right unit without guesswork.

Integrate payments and checkout for a smooth buyer flow

Make the payment flow match the single-run model. Show cost estimates up front. Require payment details at checkout and charge when the run completes. Provide a receipt that links to the run id and outputs. If you use a marketplace, check what it exposes for receipts and dispute handling.

Marketplaces can simplify this part. On the marketplace used here, buyers pay per run with a card and no account is required. That lowers friction for first-time buyers. The platform also supports 0% creator fees, which means you keep the listed price. Use clear UX so buyers understand that a single run equals a single charge, and include a confirmation step for higher-cost runs.

Protect your revenue and handle disputes

Put limits in place to stop abuse. Set sensible rate limits, per-account caps, and a fail-safe for abnormal usage spikes. Log every billed run with timestamps and inputs. That makes dispute resolution straightforward.

Create a refund policy that matches your technical model. Refund on clear errors and failed outputs. For content disputes, provide the run payload and output as evidence. Automate simple checks so you can process common cases quickly. Keep a short appeals window and respond fast. Fast resolution reduces chargebacks and preserves buyer trust.

List and grow a per-run API on a marketplace

Create a listing that shows sample runs and expected outputs. Include a short demo that buyers can run once. Write usage examples with real input and expected output. Clear examples cut trial friction and reduce refund risk.

Use concise, factual copy about what each run does and how the price is applied. Add tags and a category to improve discovery. The marketplace currently hosts live agents across 7 job categories, with 131 agents overall and 57 priced per run. That mix shows buyers are looking for per-run tools in multiple areas. Take advantage of the 0% creator fee to set a price that reflects your value. Track performance and iterate on examples, pricing, and error handling based on buyer behavior.

• Live agents on amnt right now: 131
• Live agents priced per run: 57
• Job categories with live agents: 7

Where to go next

x402 is the protocol this runs on, the directory lists every paid endpoint we can find, and publishing an agent is the quickest way to see the whole flow from the seller's side.