The best Claude model for coding

The short answer: Sonnet by default, Opus for the hard parts

The best Claude model for coding is Claude Sonnet 5 for the bulk of the work, Claude Opus 4.8 for the sessions where a wrong answer costs you hours, and Claude Haiku 4.5 for the mechanical volume in between. Pick per task, not per project: the same endpoint, key and prepaid balance serve all three tiers, so the model is just a string you set on each request.

That split follows how the tiers are built. Sonnet trades a little peak reasoning for speed and a much lower token rate — exactly what an interactive loop of edit, run, read the error, edit again rewards. Opus spends more compute per token and holds long, ambiguous threads together better. Haiku is tuned for latency and price, not depth, and that is a feature when the task has no depth to miss.

See also: Claude Opus vs Sonnet: which model should you use?

The three tiers at a glance

All four model IDs below are served at a flat 50% off official Anthropic token pricing, billed from one prepaid balance:

Opus 4.8 and Sonnet 5 both expose a 1M-token context window, so the choice between them is about reasoning depth and rate, not about how much code you can load into the prompt. Sonnet 4.6 remains available on the same key if a pinned toolchain still expects the previous generation.

When Opus 4.8 earns its higher rate

Reach for Opus when the task has real ambiguity: a cross-module refactor where choosing the right abstraction is the actual question, a design review of a system you did not write, or a debugging session where the symptom sits three layers away from the cause. In those sessions a weaker model does not fail loudly — it produces plausible code that is subtly wrong, and you pay the difference back in review time.

Opus also earns its rate in long agent runs. An agent that plans, edits and verifies for twenty minutes straight is compounding small judgment calls, and one better early decision saves whole branches of wasted tool calls. For a bounded, well-specified ticket, though, Sonnet lands the same diff faster and cheaper — escalating there is pure waste.

A practical escalation signal: if Sonnet has gone two full loops without converging — repeating the same failed fix or thrashing between approaches — stop, restart the session on Opus with the error log in the prompt, and let it re-plan from scratch.

Haiku 4.5 for the work you should not pay Sonnet rates for

A large share of the coding traffic in a real project is mechanical: lint fixes, log classification, extracting symbols from a diff, generating commit messages, first-pass test scaffolding. Haiku 4.5 handles this well at half of Sonnet 5's input rate, and its latency makes it the right engine for anything that fires on every save or every CI job.

• Pre-commit and CI hooks: lint explanations, conventional-commit messages, changelog drafts.
• Extraction and routing: pulling structured fields out of logs, stack traces or code before a bigger model reasons over them.
• High-fan-out agent steps: scoring candidate files or ranking search hits before Sonnet reads the shortlist.

The pattern that works in practice is a pipeline: Haiku filters and compresses, Sonnet does the work, Opus reviews the risky parts. Each stage pays only for the judgment it actually needs, and the cheap stages keep the expensive ones focused on a short, clean input.

Switch models per request, not per account

Because apiToken.sale exposes the standard Anthropic Messages API at https://router.apitoken.sale with your key in the x-api-key header, changing tiers is a one-line change to the model field — no new credentials, no plan change, no second provider:

curl https://router.apitoken.sale/v1/messages \
  -H "x-api-key: sk-pool-•••" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-sonnet-5",
    "max_tokens": 1024,
    "messages": [{"role":"user","content":"Refactor this function"}]
  }'

1. 01Point the client at the router once: base URL https://router.apitoken.sale, API key sk-pool-•••. Cursor, Claude Code, Continue and the Anthropic SDKs all accept a custom endpoint.
2. 02Default the tool to claude-sonnet-5 so everyday interactive work lands on the workhorse tier.
3. 03Override per session for heavy work — in Claude Code, ANTHROPIC_MODEL=claude-opus-4-8 starts that session on Opus while everything else stays on Sonnet.
4. 04In code you control, route explicitly: preprocessing calls go out with claude-haiku-4-5, the core loop with claude-sonnet-5, the final review with claude-opus-4-8.

What model routing does to a prepaid balance

The 50% discount applies identically to every tier, so routing decisions multiply rather than add: a Haiku-routed CI hook at $0.50 per million input tokens is effectively free next to an Opus review session, and that spread is the entire point of mixing models. The balance is prepaid and shared, so a heavy Opus week simply drains it faster — there is no separate plan to upgrade or downgrade, and per-request switching costs nothing but the tokens themselves.

Before committing to a routing policy, tally a typical day by tier: how many requests are mechanical, how many are real coding loops, how many are genuinely hard. Multiply each bucket by the rates in the table above and you have a defensible monthly number instead of a guess.

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