A transit station is not exotic technology — it is the same reverse-proxy-plus-gateway pattern that runs legitimate multi-model platforms. That is exactly what makes the category confusing: the plumbing is neutral and open-source, so you cannot judge a reseller by its architecture. You judge it by where the tokens come from and what happens to your data. The sections below trace the mechanism, the real source of the discount, the fraud that squares the arithmetic, the vendor and legal response, and the line to the legitimate alternatives.
The right mental model is not "cheaper vendor" but "unaudited intermediary of unknown legality serving an unverified model." Some resellers are honest bulk arbitrage; the audit evidence says many are not, and you cannot tell from the outside. If the price is far below what the tokens cost the operator upstream, that gap is being paid by someone — assume it is by you, in accuracy, data, or account risk.
DEEP READ 6 sections · cited primary sources · technical review pending
01 The mechanism, and why the software is not the problem
Technically a transit station is a reverse proxy with a management layer. You change one setting — base_url — to point at the reseller's endpoint, use the key they issue you, and your existing OpenAI/Anthropic SDK code works unchanged because the relay returns an OpenAI-compatible response after forwarding your call upstream. This is the same shape as OpenRouter, Azure OpenAI, or any legitimate gateway; the pattern itself carries no signal about legality.
The management layer is usually one of two open-source projects, both real and both neutral. one-api (songquanpeng/one-api, ~35k GitHub stars, MIT-licensed) bills itself as an LLM API management and key-redistribution system: it does channel load-balancing, per-group rate multipliers (倍率), and USD-denominated quota tokens with redemption codes. new-api (QuantumNous/new-api, AGPL-3.0) is a rewrite that adds Stripe/EPay billing and cost accounting — and its README explicitly tells operators they must lawfully obtain upstream API keys and comply with the upstream terms of service. There is even a curated directory of these gateways on GitHub.
The point of establishing this first: you cannot condemn a reseller for running a proxy or for using one-api, any more than you can condemn a shop for using a cash register. The legality and the safety live one layer up, in how the operator sourced the accounts feeding the pool, and in what the operator does with your traffic. Everything downstream in this piece is about that layer.
- one-api songquanpeng/one-api, ~35k stars, MIT. Key redistribution, channel balancing, rate multipliers, top-up codes. Neutral tooling.
- new-api QuantumNous/new-api, AGPL-3.0. Adds billing + cost accounting. README requires lawfully-sourced upstream keys and ToS compliance.
- The account pool Operators rotate many accounts behind one endpoint. Engineering is neutral; sourcing (free-tier farming, stolen cards, subscription splitting) is where the line is.
- The tell is not the tech Reverse proxy + one-api is exactly what legitimate gateways run. Judge by key provenance, data handling, and price-vs-upstream-cost — not architecture.
02 Where the discount actually comes from — the arithmetic that cannot close
Chinese technical writeups describe two channels. The "official" route (官转) is enterprise bulk buying with unified billing and dynamic scheduling; it yields something like 30-40% off and is roughly legitimate — real volume discounts, passed through. The "reverse" route (逆向) has a cost approaching zero: bulk-register free-tier accounts, reverse-engineer the web protocol, run a middle server, and rotate an account pool. Free-credit aggregation, reselling unused quota, and splitting flat-rate subscriptions (a $200/month Claude Max plan can yield more tokens per dollar than metered API) are the softer versions; stolen payment credentials are the harder one, though the AI-specific evidence for card fraud is weaker than the rest.
The reason the price is a diagnostic is arithmetic. One widely-circulated Chinese analysis put a promotional rate at roughly ¥1 for 2.85 million tokens. For a frontier model like Claude Opus, that token volume costs on the order of hundreds of yuan at the official rate — the analysis pegged it near 500 times below cost. A 30-40% discount can come from a real volume deal. A price 500x under upstream cost cannot come from efficiency; it has to come from either not paying for the tokens (fraud/theft on the sourcing side) or not delivering the tokens you paid for (model substitution on the serving side). Both happen.
This is the single most useful heuristic in the whole market: compute what the tokens would cost the reseller upstream at the official rate, and compare. A modest discount is plausibly legitimate arbitrage. A discount that implies the operator is selling below their own cost is telling you that the gap is being financed by something you would not agree to if it were disclosed.
CAVEAT The ¥1 = 2.85M-token figure and the ~500x-below-cost framing come from Chinese market analysis (Securities Times and community writeups), not from a vendor. The direction is robust — below-upstream-cost pricing is not sustainable cleanly — but treat the exact multiple as illustrative, not precise.
03 Model substitution — the best-documented fraud
The strongest evidence in this entire market is academic. Researchers at the CISPA Helmholtz Center for Information Security published "Real Money, Fake Models: Deceptive Model Claims in Shadow APIs" (arXiv 2603.01919). They audited shadow-API services with a model-fingerprinting method — comparing behavioural signatures, output distributions, and cosine distances against the genuine models. Of the endpoints they evaluated, 45.83% failed fingerprint verification: they were not serving the model they claimed. A further group showed suspicious deviations short of an outright fail.
The consequence is not abstract. On the same audit, a Gemini-2.5-flash endpoint's accuracy on MedQA (medical question answering) collapsed from 83.82% on the official API to roughly 37% through a shadow relay — the kind of degradation that is invisible in casual use and catastrophic in a high-stakes application. An independent practitioner has since documented a lightweight version of the same detection: an endpoint claiming Claude Opus that answered with a 0.7-second first token (Opus is slower), ~85 tokens/second (Sonnet-like), and a 2024 knowledge cutoff instead of Opus's later one — a cheaper model wearing the expensive model's label.
Model substitution is what makes the impossible pricing possible. If you advertise Opus and serve a small open model, your cost is a fraction of what you charge and the arithmetic closes — at the buyer's expense. For anyone building a product on a specific claimed model, this reframes the risk: "which model actually answered" stops being a given the moment access is resold, and it needs to be verified rather than assumed.
- 45.83% of audited shadow endpoints failed model-fingerprint verification — not the claimed model (CISPA).
- 83.82% -> ~37% Gemini-2.5-flash MedQA accuracy, official API vs a shadow relay. Invisible in casual use, dangerous in medicine/law.
- Fingerprinting Latency, token rate, knowledge cutoff, and tokenizer artifacts expose substitution. A cheap client-side check catches "Opus" that is actually Sonnet.
04 Active malice, data harvest, and the distillation connection
Beyond serving the wrong model, some endpoints are actively hostile. Security researchers who tested 428 stations (a mix of paid and free) reported — via Securities Times — 9 that injected malicious code into responses, 17 that attempted to steal AWS/cloud credentials, and 1 that directly targeted Ethereum assets. That reframes a transit station from "cheaper API" to "untrusted code path with a financial motive," because a response you feed into a tool-using agent or a build pipeline is an execution vector.
The quieter harm is data. Everything you send transits the operator: prompts, uploaded documents, and frequently your own upstream API keys if you are using a bring-your-own-key relay. Reporting describes proxies harvesting requests and selling the logs for training, and a named industry expert (a former Xiaomi OS AI specialist) called transit data "essentially exposed... a complete black box." For any regulated or confidential workload, that alone is disqualifying regardless of the pricing.
It is tempting to connect this directly to the industrial-scale distillation story, but the honest version is careful. Anthropic's February 2026 report disclosed roughly 24,000 fraudulent accounts generating more than 16 million Claude exchanges, attributed to DeepSeek, Moonshot, and MiniMax, all in violation of terms and regional access — and Anthropic attributes those accounts to the labs directly. The inference that transit stations were the bridge feeding those accounts is plausible and widely asserted, but it is inference, not something the report establishes. We flag the distillation crackdown as the vendor-side context, not as proof of a specific transit-station-to-lab pipeline.
CAVEAT The 428-station figures (9 malicious / 17 credential-theft / 1 crypto) are from a named security test reported by Securities Times — strong secondary, not a peer-reviewed dataset. The "transit stations fed the 24k distillation accounts" causal link is not established by Anthropic's report; do not treat it as proven.
05 Enforcement, legality, and why the account can vanish
This is not purely a caveat-emptor grey zone; it has started to draw hard enforcement. In May 2026 in Shanghai, a transit-station operator was criminally detained for 37 days and then released on bail (取保候审) for illegally obtaining and reselling overseas LLM API access via reverse-proxy and account-pool — the likely charge being 非法经营罪 (illegal business operation), with possible unlicensed value-added telecom exposure on top. The operator publicly stated he expected sentencing, disgorgement, and a fine. Chinese state media reported in June 2026 that the sector faces a rectification "storm," and legal analysis flags PIPL and Data Security Law exposure for the data-handling side.
On the vendor side, the terms are unambiguous and the account risk is concrete. Anthropic does not sell Claude commercially in mainland China, so access resold into that market violates its terms by construction — which means the account underpinning your cheap access is itself a policy violation that can be terminated. After the distillation disclosures Anthropic deployed identity verification including live biometric checks; reporting notes those are being circumvented via ID-verification services in low-income countries, but the direction of travel is clear: the accounts feeding these pools are getting harder to create and easier to sweep.
The practical implication for a buyer is supply risk you do not control. The documented exit-scam anecdotes — a developer paying about ¥45/month for "unlimited" access that died within a month with the support group vanishing; another whose ¥25/month station died in roughly 20 days during an OpenAI account-suspension sweep — are individual, unbranded cases, so do not read them as a specific operator's crime. Read them as the structural failure mode: your prepaid balance and your continuity depend on accounts and legality entirely outside your control.
CAVEAT The Shanghai case operator is not publicly named and had not been sentenced as of research; it is one strong-secondary case, not a body of case law. The exit-scam examples are individual named-developer anecdotes, not proof against any specific reseller brand.
06 The legitimate alternatives — getting the savings without the exposure
The reason the grey market is a bad trade is that the legitimate ways to cut token cost now get you most of the savings with none of the risk. Open-weight models you self-host or buy from a serverless endpoint run $0.05-$2 per million tokens with full provenance and no third party in your data path. Official first-party and cloud resale — Azure OpenAI, Google Vertex, AWS Bedrock — give you real discounts, real SLAs, and an auditable data-handling posture. OpenRouter is an authorized multi-model marketplace (note that its free tier is a thing grey stations farm, which is abuse of OpenRouter, not OpenRouter being illicit).
The distinguishing markers of the grey-vs-legitimate line are consistent: authorized key and account sourcing versus reverse-engineered endpoints and farmed accounts; KYC and a real business entity versus anonymous top-ups; an auditable data-processing agreement versus a black box; and, above all, pricing that is a plausible discount off upstream cost versus pricing that is below the operator's own cost. If a reseller clears those, it is likely in the defensible 官转 end of the market. If it cannot, the discount is being financed by something you have not been told about.
For the cost levers themselves — caching, routing, batch, agent-loop control — the sanctioned playbook does the heavy lifting: most teams can cut real spend by a large margin through configuration alone, long before anyone is tempted by a reseller. The grey market solves a problem that the legitimate stack has already largely solved.
- Open weights Self-host or serverless open-model endpoints ($0.05-$2/Mtok). Full provenance, no third party in the data path. The Chinese open-weight cluster (GLM, Kimi, MiniMax, DeepSeek) makes this stronger every quarter.
- Official cloud resale Azure OpenAI, Vertex, Bedrock — real discounts, real SLAs, auditable data handling. The boring, correct answer for regulated workloads.
- Authorized marketplace OpenRouter and similar — legitimate multi-model routing. Its free tier being farmed by grey stations is abuse of it, not a mark against it.
- The config levers Caching, routing, batch, agent-loop control cut real spend by configuration alone — see the team-level cost playbook. Solve the cost problem here, not in the grey market.