Comparison
feld.ai vs. building it yourself — GPT or Claude for document AI?
Every second evaluation we enter has already had the same meeting. Someone on the IT side dropped ten invoices into ChatGPT or Claude, got clean JSON back within a minute, and asked the reasonable question: why are we paying a vendor for this? It is a good question and it deserves a straight answer rather than a sales deflection. So here is ours, including the parts that do not favour us.
The concession first: inference is cheap
We are not going to pretend otherwise. Published list prices, retrieved 20 August 2026, in USD per million tokens:
| Provider | Model | Input | Output |
|---|---|---|---|
| Anthropic | Claude Haiku 4.5 | $1 | $5 |
| Anthropic | Claude Sonnet 5 | $2 | $10 |
| Anthropic | Claude Opus 5 | $5 | $25 |
| OpenAI | GPT-5.6 Luna | $0.20 | $1.20 |
| OpenAI | GPT-5.6 Terra | $2 | $12 |
| OpenAI | GPT-5.6 Sol | $5 | $30 |
Both providers discount batch processing by 50%; cached input costs roughly a tenth of the standard input rate. A scanned A4 page sent as an image typically consumes low thousands of input tokens plus a few hundred output tokens for the structured JSON you want back. That puts a single page at approximately one cent on Claude Sonnet 5, and below that on the smaller models.
Scaled up: 100,000 pages a year is somewhere between $500 and $1,100 of raw inference. That number is real. It is also, in our experience, about 5% of what the system costs to run.
When you should build it yourself
Four conditions. If all four hold, build it, and we mean that:
1. Low volume — hundreds of documents a month, not tens of thousands.
2. One stable document type from a small, known set of senders whose layouts do not churn.
3. No compliance burden — nothing an auditor will ask to reconstruct in three years.
4. Spare engineering capacity — a named person with time, not an intern's summer project.
Plenty of teams meet all four. For them a vendor is overhead. The trouble starts when a team meets three of four and assumes the fourth will sort itself out.
What isn't included in the API price
This is the actual answer to the original question. The model call is one step in a pipeline; the rest of the pipeline is the product.
| What you still need | Why the API doesn't give it to you |
|---|---|
| OCR for scans, photos, handwriting | Vision models read pixels expensively and imperfectly. Production systems separate the reading step from the structuring step for a reason. |
| Layout and table fidelity | Freight invoices, customs papers and multi-page annexes break naive extraction in ways that are invisible until they are expensive. |
| Calibrated confidence scores | A model will state a wrong value with the same fluency as a right one. Knowing which fields to trust is a separate engineering problem. |
| Visual grounding | When a reviewer disputes a figure, someone has to point at where on the page it came from. |
| Human-in-the-loop review UI | A reviewer needs to see the one disputed field, not the whole document. That is front-end work, not a prompt. |
| Validation against master data and ERP/TMS | A plausible-looking vendor name that does not exist in your system is worse than no answer at all. |
| Per-document-type prompt maintenance | A prompt tuned on 50 invoices from one supplier breaks on the next supplier's layout. Per type, per variant, per edge case, indefinitely. |
| An eval harness and regression suite | Without one, nobody can tell whether last Tuesday's prompt change helped or quietly broke three fields. |
| Audit trail and retention | German GoBD rules require up to ten years. API logs are not an archive. |
| Retries, rate limits, failover, queueing | Month-end is when volume spikes and when the deadline is immovable. |
| Accuracy-drift monitoring | The failure mode that shows up in month four, not week one. |
| An owner | The most common reason in-house extraction pipelines die is that the person who built it changed jobs. |
None of these is impossible. All of them are months. The honest framing is that you are not choosing between $1,100 a year and a vendor invoice — you are choosing between two engineering roadmaps.
The two arguments that actually decide it
Sovereignty: you cannot buy EU-only inference from the frontier labs. The Anthropic API is global by default. The only geography control published on the rate card is US-only inference, which carries a 1.1x multiplier across all token categories. There is no first-party EU-only option. To pin inference to European regions you go through Amazon Bedrock or Google Cloud regional endpoints — which carry a 10% premium over global endpoints and place the workload on US-owned hyperscaler infrastructure. Read that as a procurement question rather than a technical one: EU data residency from the frontier labs is a paid add-on, delivered on infrastructure owned by US companies. For a great many workloads that is entirely fine. For supplier declarations, customs documents, contracts and personnel files, it is a conversation with your DPO that does not end quickly. Our GPUs are in Feldkirch. That is not a cheaper version of the same thing; it is a different thing.
Model churn: your cost model has an expiry date you do not control. 2026 supplied two clean examples. Claude Opus 4 and Sonnet 4 were retired on 15 June 2026, announced 14 April 2026 — anyone with a production pipeline pinned to them faced a forced migration and a complete re-validation cycle, unbudgeted and on someone else's timeline. And Claude 4.7 and later models use a tokenizer that produces roughly 30% more tokens for the same text. Per-token prices did not change. Effective cost per page did. A business case built on last year's numbers broke silently, without anyone changing a line of code. You are not buying a price; you are renting one from a vendor whose roadmap you cannot see. For a chatbot, fine. For a system your auditors depend on, every model change becomes a re-validation project.
What we recommend — even if you don't buy from us
Run the prototype. Seriously — it costs almost nothing and it teaches you what your documents actually look like, which is information you need either way. Then take the prototype and ask five questions of it:
1. What is its field-level accuracy across 200 documents, not 10?
2. When it is wrong, does it tell you it is unsure — and is that signal calibrated?
3. Who reviews the uncertain cases, in what interface, and how long does each take?
4. If an auditor asks in 2029 where a figure came from, what do you show them?
5. Who owns this when its author leaves?
If the answers come out well, you have saved yourself a vendor invoice. If they come out uncomfortable, you now know the scope — and we are happy to talk. For the legal grounding: EU-sovereign document AI. For our rates: pricing.
Frequently asked questions
What does it cost to extract a page with GPT or Claude?
Very little. A scanned A4 page typically consumes low thousands of input tokens plus a few hundred output tokens. That puts a page at roughly one cent on Claude Sonnet 5 and below that on the smaller models. At 100,000 pages a year that is about $500 to $1,100 of raw inference. The number is real — in our experience it is also about 5% of what the system costs to run.
When is building it yourself the right decision?
When four conditions hold at once: low volume, one stable document type from a small known set of senders, no compliance burden an auditor will want to reconstruct in three years, and spare engineering capacity with a named owner. If all four hold, build it — a vendor is overhead.
What is not included in the API price?
OCR for scans and photos, layout and table fidelity, calibrated confidence scores, visual grounding, a human review interface, validation against master data and ERP, per-document-type prompt maintenance, an eval and regression suite, audit trail and retention, retry and failover logic, and accuracy-drift monitoring. None of it is impossible; all of it is months of engineering.
Can I get EU-only inference from OpenAI or Anthropic?
Not on their first-party APIs. The Anthropic API is global by default; the only published geography control is US-only inference, carrying a 1.1x multiplier. To pin inference to European regions you go through Amazon Bedrock or Google Cloud, where regional endpoints carry a 10% premium and place the workload on US-owned infrastructure. EU data residency from the frontier labs is a paid add-on delivered on someone else's infrastructure.
What happens when the model is deprecated?
Claude Opus 4 and Sonnet 4 were retired on 15 June 2026, announced 14 April 2026. Anyone with a production extraction pipeline pinned to them faced a forced migration and a full re-validation cycle. In addition, Claude 4.7 and later use a tokenizer producing roughly 30% more tokens for the same text: per-token prices did not change, effective cost per page did. A business case built on last year's numbers breaks silently.