Ivan CernjaClaude Code Token Cost by Backend Framework (2026)
Measured token spend across Encore, Express, Fastify, Hono, and NestJS when Claude Code builds the same realistic backend project.
How much does it cost in tokens to let Claude Code build a realistic TypeScript backend, and how does that cost vary by framework?
To put numbers on the question we ran the same claude-sonnet-4-6 agent on the same backend project (an HTTP API with persistence, a pub/sub event, a daily cron, and distributed tracing) across five frameworks (Encore, Express, Fastify, Hono, and NestJS) and across three runs (baseline, library-augmented, and rubric-graded), tracking token spend at every step. This article collects the cost-only view of the benchmark; the methodology, the rubric, and the rest of the findings are in Are TypeScript backend frameworks ready for AI agents?, and the raw transcripts are at github.com/encoredev/ai-backend-benchmark.
Methodology
Each framework runs on its own VM with the same Postgres setup and the same claude-sonnet-4-6 model running through Claude Code. The agent works through three linked tasks (HTTP API and persistence, pub/sub and cron, tracing and production-readiness) and we repeat each framework three times for each run. We capture every artifact, including the per-task token usage Claude Code emits, and we compute cost at the published Sonnet 4.6 rate. Numbers below are medians across the three repeats unless stated otherwise. Run 3 was a single repeat per framework because we were looking for a directional read on whether grading the rubric in the tests moved the agent, not another full sweep.
Totals across three runs
| Framework | Total token cost across all three runs |
|---|---|
| Encore | $6.29 |
| NestJS | $12.69 |
Encore and NestJS are the two endpoints we report explicitly. Express, Fastify, and Hono sit between them; their full per-framework totals are derivable from the per-run transcripts in the benchmark repo.
Per-run highlights
In Run 1 Hono was the cheapest framework of the benchmark at $1.55 per run, Encore was at $1.96, and NestJS was the most expensive at $2.61 median with one repeat running to $4.45 (the highest single repeat on the baseline run).
In Run 2 every non-Encore framework regressed. With pg-boss, drizzle-kit, and pino pre-installed in the starter, the agent burned turns trying to integrate the libraries cleanly and the cost on every framework other than Encore went up. None of the four landed a first-try-green run across three repeats.
In Run 3, with the production-readiness rubric written into the test suite and a higher per-task turn budget, the costs spread further. Fastify hit every rubric check at $4.60 per run, Encore hit every check at $2.58 per run, and NestJS finished at 30 of 36 checks at $5.95 per run.
Why Encore stays flat
Encore's per-run cost barely moved across the three runs, because the production-readiness checks the test suite added in Run 3 were already encoded in the primitives the agent had used in Run 1. A retryPolicy: { maxRetries: 3 } on the existing Subscription satisfied the DLQ check; switching from console.log to encore.dev/log satisfied the structured-logging check; the numbered SQL migrations the agent had already written satisfied the versioned-migrations check.
Why the other four frameworks climbed
The other four frameworks paid two distinct kinds of cost on top of the baseline. In Run 2 they paid library-integration cost, with the agent burning turns wiring pg-boss, drizzle-kit, and pino into the project and debugging when the wiring drifted. In Run 3 they paid rubric-iteration cost, with the agent making further changes to land the production-readiness checks on top of the library integration. NestJS additionally paid module-wiring cost in both runs, because cross-cutting changes in NestJS involve maintaining providers arrays and decorators that the agent gets wrong more often than it gets right.
What it means for a monthly bill
The per-run differences in the benchmark project into a real monthly bill when a team runs this kind of agent-driven workflow daily. A team of 10 engineers running roughly one full backend feature per engineer per day at $2 per run lands at around $440 per month; the same team on a framework that costs $4 per run lands at around $880, and the more expensive framework is also the one whose first-draft code is less likely to be safe to deploy without further intervention.
Reproduce the numbers
Clone the repo, run the benchmark on your own infrastructure, or recompute against a different model: github.com/encoredev/ai-backend-benchmark.