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Model infoModelsSnapshot: 15 Oct 2026

ByteDance / Seed

Seed 1.8 (251228)

Seed 1.8 language-model revision 251228, with documented reasoning and tool calling through ModelArk.

deprecatedClosed weightsText generation
Official documentation (opens in a new tab)Reviewed 15 Oct 2026
12 of 19 specification fields collected
Input token limit224KSee specification notes below
Maximum output64KSee specification notes below
Input / 1M tokens$0.25BytePlus ModelArk
Output / 1M tokens$2.00USD · observed 12 Oct 2026

Specifications

Provider-documented facts. “Not collected” means we have not verified that field yet, not that the feature is unsupported.

Context / input limit
256KSource for Context / input limit (opens in a new tab)

Provider K-token notation retained. Output limit includes chain-of-thought tokens.

Maximum output
64KSource for Maximum output (opens in a new tab)

Provider K-token notation retained. Output limit includes chain-of-thought tokens.

Input modalities
Text, Image, VideoSource for Input modalities (opens in a new tab)
Structured output
SupportedSource for Structured output (opens in a new tab)

The catalog labels structured output beta. JSON schema is explicitly recommended for the April 2026 Mini and Lite releases.

Streaming
Not collected
Fine-tuning
Not collected
Knowledge cutoff
Not collected
Release date
Not collected
Parameters
Not collected
Architecture
Not collected
Languages
Not collected
Maximum input tokens
224KSource for Maximum input tokens (opens in a new tab)

Provider K-token notation retained. Output limit includes chain-of-thought tokens.

Maximum thinking tokens
32KSource for Maximum thinking tokens (opens in a new tab)

Provider K-token notation retained. Output limit includes chain-of-thought tokens.

Published request quota
30K Max RPM; 1500K Max TPMSource for Published request quota (opens in a new tab)

Published quota, not a throughput or latency benchmark.

Access & pricing

Prices belong to an endpoint and billing tier. A provider listing does not guarantee access for every account or region.

BytePlus ModelArk · standard

Provider source (opens in a new tab)
API model ID
seed-1-8-251228
Access
Deprecated: new endpoint creation ended September 15, 2026. Existing service is scheduled to stop November 11, 2026.
Regions
Not collected
Endpoint availability
Deprecated: new endpoint creation ended September 15, 2026. Existing service is scheduled to stop November 11, 2026.Source for Endpoint availability (opens in a new tab)
INPUT / 1M TOKENS$0.25
OUTPUT / 1M TOKENS$2.00

standard non-audio rate table. Full prompt length selects the rate for the entire request; thinking tokens count toward output. Published rate for a deprecated model; check endpoint availability and account eligibility. Finite pricing bounds do not override modality-specific API input limits. Cached input price: $0.05 / 1M tokens (base tier).

Pricing by prompt length, USD / 1M tokens
Input lengthInputOutputCached input
Prompt length [0, 128] K tokens$0.25$2.00$0.05
Prompt length (128, 256] K tokens$0.50$4.00$0.05
USD · observed 12 Oct 2026 · Pricing evidence (opens in a new tab)
Published billing units · original currency · observed 12 Oct 2026
CategoryUsageRateUnit
CachingExplicit cache storage1$0.00831M tokens/hour
CachingExplicit cache storage2$0.00831M tokens/hour

Rate conditions

  1. Prompt length [0, 128] K tokens. Explicit cache only; implicit storage is free. Partial natural hours billed as whole hours. Pricing-table units used; the cache guide uses a different generic unit description.
  2. Prompt length (128, 256] K tokens. Explicit cache only; implicit storage is free. Partial natural hours billed as whole hours. Pricing-table units used; the cache guide uses a different generic unit description.
Pricing source (opens in a new tab)

Data & enterprise terms

Retention, training use, regional processing and enterprise terms have not been summarized for this endpoint.

BytePlus ModelArk · batch

Provider source (opens in a new tab)
API model ID
seed-1-8-251228
Access
Deprecated: new endpoint creation ended September 15, 2026. Existing service is scheduled to stop November 11, 2026.
Regions
Not collected
Endpoint availability
Deprecated: new endpoint creation ended September 15, 2026. Existing service is scheduled to stop November 11, 2026.Source for Endpoint availability (opens in a new tab)
INPUT / 1M TOKENS$0.125
OUTPUT / 1M TOKENS$1.00

batch non-audio rate table. Full prompt length selects the rate for the entire request; thinking tokens count toward output. Published rate for a deprecated model; check endpoint availability and account eligibility. Finite pricing bounds do not override modality-specific API input limits. Cached input price: $0.05 / 1M tokens (base tier).

Pricing by prompt length, USD / 1M tokens
Input lengthInputOutputCached input
Prompt length [0, 128] K tokens$0.125$1.00$0.05
Prompt length (128, 256] K tokens$0.25$2.00$0.05
USD · observed 12 Oct 2026 · Pricing evidence (opens in a new tab)

Data & enterprise terms

Retention, training use, regional processing and enterprise terms have not been summarized for this endpoint.

Caching

Caching can reuse earlier input processing. Availability, lifetime and billing depend on the endpoint. A cache hit still generates a new response.

01 / INITIAL INPUTProcess & retain

The system processes eligible input and retains reusable state.

02 / LATER REQUESTCheck available state

Reuse depends on matching input, session state and the cache policy.

03 / CACHE HITReuse & generate

Reusing state can reduce repeated work. Any charges follow the billing rules below.

BytePlus ModelArk · standard

seed-1-8-251228
Documented
Support evidence (opens in a new tab)
How it works
Implicit: Batch API (Chat), Batch Inference API (Job). Explicit: Responses API, Prefix caching, Session caching.Source for How it works (opens in a new tab)
Minimum reusable input
Implicit: 1,024 tokens. Explicit prefix: 256 tokens. Session cache has no minimum stated.Source for Minimum reusable input (opens in a new tab)
Lifetime & refresh
Implicit retention is dynamic. Responses explicit caching expires at expire_at, at most 7 days after creation; reuse does not extend expiration.Source for Lifetime & refresh (opens in a new tab)
How to enable it
Implicit caching is automatic. Responses explicit caching requires store=true and caching.type=enabled; reuse the stored response/prefix identifier.Source for How to enable it (opens in a new tab)
Usage fields
Inspect cached_tokens in the response usage details to distinguish hits from uncached input.Source for Usage fields (opens in a new tab)
Billing rules
Cached-input rates depend on prompt length. Implicit storage is free. Explicit storage is billed separately, rounded to natural hours.Source for Billing rules (opens in a new tab)
Limits & data boundaries
Explicit caching replaces implicit caching for that request. The older Context API uses a different, sliding TTL; its default is not copied to Responses caching.Source for Limits & data boundaries (opens in a new tab)
Cache reads, writes & storage
ChargeApplies toRate / unit
Cache read1Text tokens · Prompt length [0, 128] K tokens$0.05 / 1M tokensPricing evidence (opens in a new tab)
Cache read1Text tokens · Prompt length (128, 256] K tokens$0.05 / 1M tokensPricing evidence (opens in a new tab)
Explicit cache storage2Caching$0.0083 / 1M tokens/hourPricing evidence (opens in a new tab)
Explicit cache storage3Caching$0.0083 / 1M tokens/hourPricing evidence (opens in a new tab)

Rate conditions

  1. standard non-audio rate table. Full prompt length selects the rate for the entire request; thinking tokens count toward output. Published rate for a deprecated model; check endpoint availability and account eligibility. Finite pricing bounds do not override modality-specific API input limits.
  2. Prompt length [0, 128] K tokens. Explicit cache only; implicit storage is free. Partial natural hours billed as whole hours. Pricing-table units used; the cache guide uses a different generic unit description.
  3. Prompt length (128, 256] K tokens. Explicit cache only; implicit storage is free. Partial natural hours billed as whole hours. Pricing-table units used; the cache guide uses a different generic unit description.

Observed 12 Oct 2026. Write rates and storage fees are different charges; use the billing rules above.

Caching reviewed 12 Oct 2026

BytePlus ModelArk · batch

seed-1-8-251228
Documented

A cached-input rate is published for this service tier; this does not imply the standard endpoint’s explicit-storage controls.

Support evidence (opens in a new tab)
How it works
Not collected
Minimum reusable input
Not collected
Lifetime & refresh
Not collected
How to enable it
Not collected
Usage fields
Not collected
Billing rules
Use the cached-input rate for this service tier and prompt-length band.Source for Billing rules (opens in a new tab)
Limits & data boundaries
Not collected
Cache reads, writes & storage
ChargeApplies toRate / unit
Cache read1Text tokens · Prompt length [0, 128] K tokens$0.05 / 1M tokensPricing evidence (opens in a new tab)
Cache read1Text tokens · Prompt length (128, 256] K tokens$0.05 / 1M tokensPricing evidence (opens in a new tab)

Rate conditions

  1. batch non-audio rate table. Full prompt length selects the rate for the entire request; thinking tokens count toward output. Published rate for a deprecated model; check endpoint availability and account eligibility. Finite pricing bounds do not override modality-specific API input limits.

Observed 12 Oct 2026. Write rates and storage fees are different charges; use the billing rules above.

Caching reviewed 12 Oct 2026

What the measurements say

No benchmark observations have been added for this model. We do not turn a vendor description into a performance score.

Latency and throughput depend on the host, request size, reasoning settings and load. There is no measured speed or global usage figure in this record.

The record behind the model

Why it is included

Inferred from the named native hosted API offering and cross-check of ByteDance and ByteDance-Seed public repositories. No matching downloadable checkpoint was found. This is not an explicit published weight-license declaration.

Classification evidence (opens in a new tab)

Lifecycle dates

BytePlus deprecation announced8 Sept 2026Source (opens in a new tab)
BytePlus new endpoint creation ended15 Sept 2026Source (opens in a new tab)
BytePlus service shutdown scheduled11 Nov 2026Source (opens in a new tab)

Sources reviewed